Testwiki:Manual of Style/Dates and numbers పేజీ సోర్సు చూడండి

{{Redirect|WP:NUMBERS|the Wikiproject|Wikipedia:WikiProject Numbers|the notability guideline|Wikipedia:Notability (numbers)}}
{{MoS guideline|MOS:NUM|WP:MOSNUM}}
<noinclude>{{pp-move-indef}}</noinclude>
{{Style}} 
<!-- 
PLEASE MAKE MINOR CHANGES TO THIS TEXT ALSO TO THE EQUIVALENT TEXT AT MOS. 
MORE SIGNIFICANT CHANGES, ESPECIALLY TO THE ACTUAL STYLE RECOMMENDATIONS, NEED TO BE FLAGGED AT THE WT:MOS TALK PAGE BEFORE IMPLEMENTATION HERE AND AT MOS, UNLESS THEY INVOLVE SECTIONS HERE THAT HAVE NO EQUIVALENT AT MOS (e.g. GEOGRAPHICAL COORDINATES).

FORMATTING: This page makes heavy and very particular use of a lot of specific formatting. To avoid confusion concerning the proper formatting of units, symbols, values, variables, code, etc., please observe the following markup conventions on this page:
- Use {{xt}} to mark up positive examples or required text.
- Use {{!xt}} to mark up negative examples or deprecated items.
- Use {{xtn}} to mark up items that may or may not be applied depending on context.
- Use {{xtg}} to mark up items that are very rarely applied – dubious, deprecated, disputed, only used in one context (this template may not be needed on this page but is available).
- Use double quotes to mark up words-as-words, "scare-quoting", and quoted sources, but not for unusual purposes. Italics are used heavily on this page for many other things, so do not use them for words-as-words.
- Use {{em}} to mark up emphasis.
- Reserve plain ''italic'' only for conventional stylistic, non-semantic use of italics (e.g. for titles of major published works, foreign phrases, etc.; see above about words-as-words).
- Use '''bold''' to mark up inline headers.
- Use {{strong}} to mark up strong emphasis (rarely needed; {{em}} will usually suffice).
- Use <code>...</code> (or <code><nowiki>...</nowiki></code> if needed) to mark up code examples, including individual special characters. Do not use <tt>; this element no longer exists in HTML5.
- Use {{var}} to mark up variables and variable input, not {{smallcaps}}, ''...'', or other markup.
- Use {{tlx}} to illustrate or name templates (or use {{tl}} if nested inside <code>...</code>).
- Use <kbd>...</kbd> in running prose to indicate editor input choices for templates (not necessary in actual code examples inside <code>...</code>)
- Use <samp>...</samp> in running prose to indicate example code output that should be monospaced, if the need arises.
- Use spaced en dashes, not run-together em dashes, especially with markup examples, so the dash cannot be confused as being part of the example.
- Use {{crossref}} for cross-references to other sections or pages. This produces consistent formatting, and helps identify cross-references in the code for periodic checking against "advice forking".
- Avoid italicization other than as specified above.
- Avoid {{shy}} in or near examples; should probably only be used inside tables, when width is a concern.
- Do not mark up mention of units and the like outside the context of advice about their use. Example: 'Use {{xtn|m}} for "minute" only where there is no danger of confusion with meter'
 ["meter" is not marked up here per this convention; "m" is marked up with {{xtn}} for conditional use; "minute" is double-quoted for words-as-words use].
-->

This page guides the presentation of numbers, dates, times, measurements, currencies, coordinates, and similar material in articles. Its aim is to promote clarity and cohesion; this is especially important {{em|within}} an article. The goal is to make the whole encyclopedia easier and more intuitive to use.

Where this manual provides options, consistency should be maintained within an article unless there is a good reason to do otherwise. The [[Wikipedia:Arbitration Committee|Arbitration Committee]] has ruled that editors should not change an article from one guideline-defined style to another without a substantial reason unrelated to mere choice of style, and that revert-warring over optional styles is unacceptable.{{efn|1=See [[Wikipedia:Arbitration Committee|Arbitration Committee]] statements of principles in [[Wikipedia:Arbitration/Index/Cases|cases]] on style-related edit warring in [[Wikipedia:Requests_for_arbitration/Jguk#Principles|June 2005]], [[Wikipedia:Requests for arbitration/jguk 2#Principles|November 2005]], and [[Wikipedia:Requests for arbitration/Sortan#Principles|February 2006]].}} If discussion cannot determine which style to use in an article, defer to the style used by the first major contributor.
{{TOC limit|4}}

==General notes==
===Quotations, titles, etc.<span id="ExternException"></span>===
{{see also|WP:MOSQUOTE}}
Quotations, titles of books and articles, and similar "imported" text should be faithfully reproduced, even if they employ formats or units inconsistent with these guidelines or with other formats in the same article. If necessary, clarify via [bracketed interpolation], article text, or footnotes.
* It is acceptable to change other date formats in the same article to provide consistency, so long as those changes would otherwise be acceptable.<!-- "To provide consistency" with what? Is this suggesting changing the article to match a quote or quotes? -->

===Non-breaking spaces===
Guidance on the use of [[non-breaking space]]s ("hard spaces"){{snd}}<code>&amp;nbsp;</code>, {{tlx|nbsp}}, <code>&amp;thinsp;</code>, {{tlx|thinsp}}{{snd}}is given in some sections below; {{tlx|nowrap}} may also be useful in controlling linebreaks in some situations. Not all situations in which hard spaces or {{tlx|nowrap}} may be appropriate are described. {{crossref|For further information see {{section link|Wikipedia:Manual of Style|Non-breaking spaces}} and [[Wikipedia:Line-break handling]].}}

==Chronological items==

===Statements likely to become outdated===
{{Shortcut|MOS:DATED|MOS:EPHEMERAL|MOS:CURRENT}}
{{See also|Wikipedia:Manual of Style/Words to watch#Relative time references|Wikipedia:As of}}

Except on pages updated regularly (e.g. [[Wikipedia:How the Current events page works|the "Current events" portal]]), terms such as {{!xt|now}}, {{!xt|currently}}, {{!xt|to date}}, {{!xt|so far}}, {{!xt|soon}}, and {{!xt|recently}} should usually be avoided in favor of phrases such as {{xt|during the 1990s}}, {{xt|since 2010}}, and {{xt|in August 1969}}. For current and future events, use phrases like {{xt|as of {{CURRENTMONTHNAME}} {{CURRENTYEAR}} }} or {{xt|since the beginning of {{CURRENTYEAR}} }} to signal the time-dependence of the information.
Using {{tlx|as of|{{CURRENTYEAR}} }} will produce the text {{xt| {{as of| {{CURRENTYEAR}} }} }}, with the additional benefit of putting the article in a category flagging it for periodic review. A full date is specified with {{tlc|as of|{{CURRENTYEAR}}|{{CURRENTMONTH}}|{{CURRENTDAY}} }}.<!--Just to be clear, when using {{as of}}, hard-code the current , year, month, or date e.g. {{as of|2016|02|15}} -- do //not// code {{as of| {{CURRENTYEAR}}|{{CURRENTMONTH}}|{{CURRENTDAY}} }}, which would (at best) defeat the purpose of {{as of}}, and (at worst) cause the internet to melt down in a cosmic infinite loop--> 
However, do not replace {{xt|since the beginning of 2005}} with {{tlc|as of|2005}} because some information (the {{em|beginning}} of 2005) would be lost; instead, make use of the template's alternate-text parameter: {{tlx|as of|2005|alt{{=}}since the beginning of 2005}}.

Relative-time expressions are acceptable for very long periods, such as geological epochs: {{xt|Humans diverged from other primates long ago, but [[wikiquote:Samuel Butler (novelist)#legislature|only recently developed state legislatures]]. }}

=== Dates, months, and years===
{{anchors|dates|years|Years|Months|Dates and years|Dates, months and years}}
{{shortcut|MOS:YEAR|MOS:DATE|MOS:DATEFORMAT}}

*These requirements do not apply to dates in quotations or titles; {{crossref|see {{section link|Wikipedia:Manual of Style|Quotations}}}}. 
*Special rules apply to citations; {{crossref|see {{section link|Wikipedia:Citing sources|Citation style}}}}.
*See also [[Wikipedia:Overview of date formatting guidelines]].

====Formats<span id="Acceptable date formats"></span><span id="Date formats"></span>====
{| class="wikitable"
|+ Acceptable date formats
|-
! style="width:40pt;"<!--undersized width specification means actual column width determined by widest word/unbreakable string in the column-->| General use
! style="width:40pt;"| {{nowrap|Only where brevity is helpful}}<br/>{{small|(refs,{{efn|1=Only certain citation styles use abbreviated date formats. By default, Wikipedia does not abbreviate dates. [[Wikipedia:Citing sources#Citation style|Use a consistent citation style within any one article.]]}} tables, {{nobr|infoboxes, etc.)}} }}
! Comments<!--no width specification means this column will pick up all remaining horizontal width-->
|-
| {{xt|2{{nbsp}}September 2001}}
| {{xt|2{{nbsp}}Sep 2001}}
|
|-
| {{xt|September{{nbsp}}2, 2001}}
| {{xt|Sep{{nbsp}}2, 2001}}
| A comma follows the year unless [[Wikipedia:Manual of Style#Commas|followed by other punctuation that replaces the comma]]: {{unordered list| {{xt|The weather on March 12, 2005, was clear and warm}} | {{xt|Everyone remembers July{{nbsp}}21, 1969{{snd}}when man first landed on the Moon }} }}
|-
| {{xt|2{{nbsp}}September}}
| {{xt|2{{nbsp}}Sep}}
| rowspan=2 | Omit year only where there is no risk of ambiguity: {{ unordered list | {{xt|The 2012 London Olympics ran from 25{{nbsp}}July to 12{{nbsp}}September}} | {{xt|January{{nbsp}}1 is New Year's Day}} }}
|-
| {{xt|September{{nbsp}}2}} 
| {{xt|Sep{{nbsp}}2}}
|-
| {{nobr|<small>''No equivalent for {{nobr|general use}}''</small>}}
| {{xt|2001-09-02}}
| Use {{nowrap|{{var|yyyy}}-{{var|mm}}-{{var|dd}}}} format only with [[Gregorian calendar|Gregorian]] dates from 1583 onward.{{efn|1=All-numeric {{nowrap|{{var|yyyy}}-{{var|mm}}-{{var|dd}}}} dates might be assumed to follow the [[ISO 8601]] standard, which mandates the Gregorian calendar. Also, technically all must be four-digit years, but Wikipedia is unlikely to ever need to format a far-future date beyond the year 9999.}}
|-
| {{xt|September 2001}}
| {{xt|Sep 2001}}
|
|}

{{shortcut|MOS:UNLINKDATES|MOS:BADDATE}}{{anchor|Date autoformatting|Autoformatting and linking|Linking and autoformatting of dates|Things to avoid}}
* Dates should be linked only when they are germane to the subject {{crossref|(as discussed at {{section link|Wikipedia:Linking|Chronological items}})}}.{{efn|1=The [[Wikipedia:Manual of Style/Dates and numbers/Date autoformatting|routine linking of dates]] is deprecated. This change was made August 24, 2008, on the basis of [[Wikipedia talk:Manual of Style (dates and numbers)/Archive D6#Again calling for date linking to be deprecated|this archived discussion]]. It was ratified in two December 2008 RfCs: [[Wikipedia:Manual of Style/Dates and numbers/Three proposals for change to MOSNUM]] and [[Wikipedia:Manual of Style/Dates and numbers/Date Linking RFC]].}}
* For issues related to dates in sortable tables, {{crossref|see {{section link|Help:Sorting|Date sorting problems}}}}, or consider using {{nowrap|{{tlx|sort|2008-11-01|1 Nov 2008}}}} or {{nowrap|{{tlx|dts|Nov 1, 2008}}.}}
* Phrases such as {{xt|[[Fourth of July]]}} (or {{xt|July{{nbsp}}Fourth}}, but not {{!xt|July{{nbsp}}4th}}), {{xt|[[Cinco de Mayo]]}}, {{xt|[[Seventh of March Speech]]}} and {{xt|[[Independence Day (Brazil)|Sete de Setembro]]}} are proper names, to which rules for dates do not apply ({{xt|A typical Fourth of July celebration includes fireworks}}). 

{{shortcut|MOS:DATESNO}}{{anchor|Unacceptable date formats}}
{| class="wikitable"
|+ Unacceptable date formats (except in [[#ExternException|external titles and quotes]])
|-
! style="width:95pt;"| [[File:X mark.svg|11px|link=|alt=]] Unacceptable
! style="width:80pt;"| [[File:Yes check.svg|11px|link=|alt=]] Acceptable
! Comments
|-
|{{!xt|Sep'''.'''<!-- ←Bold to make dot more obvious.--> 2}}
|{{xt|Sep 2}}
|rowspan=2 | Do not add a dot to the day or to an abbreviated month{{efn|1=For consensus discussion on abbreviated date formats like "Sep 2", see {{section link|Wikipedia talk:Manual of Style/Archive 151|RFC: Month abbreviations}}. }}
|-
| {{!xt|9'''.'''<!-- ←Bold to make dot more obvious.--> June}}
| rowspan=5 | {{xt|9{{nbsp}}June}} or {{xt|June{{nbsp}}9}}
|-
| {{!xt|9 june}}<br />{{!xt|june 9}}
| Months are capitalized
|-
| {{!xt|9th June}}<br />{{!xt|June 9th}}<br />{{nowrap|{{!xt|the 9th of June}}}}
| Do not use ordinals ({{!xt|1st}}, {{!xt|2nd}}, {{!xt|3rd}}, etc.)
|-
|{{!xt|09-06}}<br>{{!xt|06-09}}
| Do not use these formats
|-
| {{!xt|09 June}}<br />{{!xt|June 09}}
| Do not use a leading zero in month or day{{nbsp}}...
|-
| {{!xt|2007-4-15}}
| rowspan=5| {{xt|2007-04-15}}
| ... except in all-numeric {{nowrap|({{var|yyyy}}-{{var|mm}}-{{var|dd}}) format}}
|-
| {{!xt|2007/04/15}}
| Do not use separators other than hyphens
|-
| {{!xt|07-04-15}}
| Do not abbreviate year to two digits
|-
| {{!xt|15-04-2007}}<br />{{!xt|04-15-2007}}<br/>{{!xt|2007-15-04}}<!-- The specific combination of values "04" and "15" (one below 12, the other above 12) used in these "Unacceptable" examples was chosen to allow there to be a single unambiguous entry in the "Acceptable" column. --> 
| Do not use {{nowrap|{{var|dd}}-{{var|mm}}-{{var|yyyy}}}}, {{nowrap|{{var|mm}}-{{var|dd}}-{{var|yyyy}}}} or {{nowrap|{{var|yyyy}}-{{var|dd}}-{{var|mm}}}} formats.{{efn|1=These formats cannot, in general, be distinguished on sight, because there are usages in which ''{{nowrap|03-04-2007}}'' represents March{{nbsp}}4, and other usages in which it represents April{{nbsp}}3. In contrast, there is no common usage in which ''{{nowrap|2007-04-03}}'' represents anything other than April{{nbsp}}3.}}
|-
| {{!xt|2007 April 15}}<br />{{!xt|2007 Apr 15}}
| Do not use these formats.
|-
| {{!xt|7/2001}}<br />{{!xt|7-2001}}<br />{{!xt|07-2001}}<br />{{!xt|2001-07}}<br />{{!xt|2001 July}}<br />{{!xt|July of 2001}}
| rowspan=2| {{xt|July 2001}}
| Do not use these{{nbsp}}formats.
|-
| {{!xt|July''',''' 2001}}
| rowspan=2| No comma between month and{{nbsp}}year
|-
| {{!xt|3 July''',''' 2001}}
| {{xt|3{{nbsp}}July 2001}}
|-
| {{!xt|July 3 2001}}
| {{xt|July{{nbsp}}3''',''' 2001}}
| Comma required between day and{{nbsp}}year
|-
| {{!xt|the{{nbsp}}'''{{'}}'''97 elections}}<br/>{{!xt|the{{nbsp}}97 elections}}
| {{xt|{{nowrap|the 1997 elections}}}}
| Do not abbreviate year
|-
| {{!xt|Copyright MMII}}
| {{xt|Copyright 2002}}
| [[Roman numerals]] are not normally used for{{nbsp}}dates
|-
| {{!xt|{{nowrap|Two thousand one}}}}
| {{xt|2001}}
|  rowspan=2| Years and days of the month are not normally written in{{nbsp}}words
|-
| {{!xt|the first of May}}<br>{{!xt|May the first}}
| {{nowrap|{{xt|May{{nbsp}}1}} or {{xt|1{{nbsp}}May}}}}
|-
| {{!xt|June 0622}}
| {{xt|June 622}}
| Do not zero-pad years
|-
| {{!xt|{{nowrap|sold in the year 1995}}}}
| {{xt|sold in 1995}}
| Use "the year" only where needed for clarity {{nowrap|({{xt|About 1800{{nbsp}}ships arrived in the year 1801}})}}
|}

=====Consistency=====
{{anchor|Format consistency}}
{{shortcut|MOS:DATEUNIFY}}
* '''Dates in article body text''' should all use the same format: {{xt|She fell ill on {{nobr|25 June 2005}} and died on {{nobr|28 June}}}}, but not {{!xt|She fell ill on {{nobr|25 June 2005}} and died on {{nobr|June 28}}}}.
* '''Publication dates''' in an article's citations should all use the same format, which may be:
** the format used in the article body text,
** an abbreviated format from the [[#Dates and years|"Acceptable date formats" table]], provided the day and month elements are in the same order as in dates in the article body, or
** the format expected in the [[Wikipedia:Citing sources#Citation style|citation style]] being used (however, all-numeric date formats other than {{nowrap|{{var|yyyy}}-{{var|mm}}-{{var|dd}}}} must still be avoided).
: For example, publication dates within a single article might be in one, but only one, of these formats (among others):
:: {{xt|Jones, J. (20 September 2008)}}
:: {{xt|Jones, J. (September 20, 2008)}}

* '''Access and archive dates''' in an article's citations should all use the same format, which may be:
** the format used for publication dates in the article;
** the format expected in the citation style adopted in the article (e.g. {{nobr|{{xt|20 Sep 2008}});}} or 
** {{nowrap|{{var|yyyy}}-{{var|mm}}-{{var|dd}}}}
: For example, access/archive dates within a single article might be in one, but only one, of these formats (among others):
:: {{xt|Jones, J. (September 20, 2008){{nbsp}}... Retrieved February 5, 2009.}}
:: {{xt|Jones, J. (20 Sep 2008){{nbsp}}... Retrieved 5 Feb 2009.}}
:: {{xt|Jones, J. (20 September 2008){{nbsp}}... Retrieved 2009-02-05.}}
:When a citation style does not expect differing date formats, it is permissible to normalize publication dates to the article body text date format, and/or access/archive dates to either, with date consistency being preferred.

=====Strong national ties to a topic=====
{{shortcut|MOS:DATETIES|WP:MILFORMAT}}
{{See also|Wikipedia:Manual of Style#Strong national ties to a topic}}
* Articles on topics with strong ties to a particular English-speaking country should generally use the date format most commonly used in that nation. For the United States this is (for example) {{nobr|{{xt|July 4, 1976}}}}; for most other English-speaking countries it is {{nobr|{{xt|4 July 1976}}}}.
* Articles related to Canada or Israel may use either format with (as always) consistency within each article. {{see below|Retaining existing format}}
* In some topic areas, the customary format differs from the usual national one: for example, articles on the modern US military, including US military biographical articles, use day-before-month, in accordance with US military usage.

=====Retaining existing format<span id="Retaining the existing format"></span>=====
{{shortcut|MOS:DATERET|MOS:DATEVAR}}
{{See also|Wikipedia:Manual of Style#Retaining the existing variety|}}

* If an article has evolved using predominantly one date format, this format should be used throughout the article, unless there are reasons for changing it based on strong national ties to the topic or consensus on the article's talk page.
* The date format chosen by the first major contributor in the early stages of an article should continue to be used, unless there is reason to change it based on strong national ties to the topic or consensus on the article's talk page.
* Where an article has shown no clear sign of which format is used, the first person to insert a date is equivalent to "the first major contributor".

====Era style<span id="Year numbering systems"></span><span id="Eras and other very long periods"></span>====
{{shortcut|MOS:ERA|MOS:BCE}}
* The default [[calendar era]] is the [[Dionysian era|Western Dionysian era system]], a year-numbering system also known as the Western Christian era (represented by {{xt|[[Anno Domini|BC and AD]]}}), or the [[Common Era]] (represented by {{xt|[[Common Era|BCE and CE]]}}).
** {{xtn|BC}} and {{xtn|AD}} are the traditional ways of designating eras. {{xtn|BCE}} and {{xtn|CE}} are common in some scholarly texts and in certain topic areas. Either convention may be appropriate for use in Wikipedia articles.
*** Use either the BC{{ndash}}AD or the BCE{{ndash}}CE notation consistently within the same article. Exception: do not change [[MOS:QUOTE|direct quotations]], titles, etc.
*** Do not change the established era style in an article unless there are reasons specific to its content. Seek consensus on the talk page {{em|before}} making the change. Open the discussion under a subhead that uses the word "era". Briefly state why the style is inappropriate for the article in question. A personal or categorical preference for one era style over the other is not justification for making a change.
*** {{xtn|BCE}} and {{xtn|CE}} or {{xtn|BC}} and {{xtn|AD}} are written in upper case, unspaced, without a full stop (period, <code>.</code>), and separated from the numeric year by a space ({{xt|5{{nbsp}}BC}}, not {{!xt|5BC}}). It is advisable to use a [[Wikipedia:Manual of Style#Non-breaking spaces|non-breaking space]].
*** {{xtn|AD}} may appear before or after a year ({{xt|AD{{nbsp}}106}}, {{xt|106{{nbsp}}AD}}); the other abbreviations appear only after ({{xt|106{{nbsp}}CE}}, {{xt|3700{{nbsp}}BCE}}, {{xt|3700{{nbsp}}BC}}).
*** In general, do not use {{xtn|CE}} or {{xtn|AD}} unless required to avoid ambiguity (e.g. {{xt|The Norman Conquest took place in 1066}} not {{!xt|1066{{nbsp}}CE}} nor {{!xt|AD{{nbsp}}1066}}) or awkwardness {{nobr|({{xt|January 1, 1 AD}} }} not {{nobr|{{!xt|January 1, 1}}).}} On the other hand, {{xt|[[Plotinus]] lived at the end of the 3rd century AD}} will avoid confusion, and depending on context one- and two-digit years may look more natural with an era marker ({{xt|born in 2{{nbsp}}AD}}). Also, in {{xt|He did not become king until 55{{nbsp}}CE}} the era marker makes it clear that ''55'' does not refer to the new king's age (or write {{xt|He did not become king until the year 55}}). If the era is shown for the initial date in a range, then use it for the final date as well: not {{nobr|{{!xt|from 450 BCE to 200}}}} but {{nobr|{{xt|from 450 to 200 BCE}}}} or {{nobr|{{xt|from 450 BCE to 200 BCE}}}} (and definitely {{nobr|{{xt|from 100 BCE to 200 CE}}}}). {{See below|Ranges}}
* '''Uncalibrated (bce) radiocarbon dates:''' [[Calibrated years|Calibrated and uncalibrated]] dates can diverge widely, and some sources distinguish the two only via {{xtn|BCE}} or {{xtn|BC}} (for calibrated dates) versus {{xt|bce}}, {{xtn|bc}} or {{xtn|b.c.}} (uncalibrated). Avoid giving uncalibrated dates except in direct quotations, and even then a footnote or square-bracketed note [like this] should note that the date is uncalibrated or (ideally) give the calibrated date.
* '''BP or YBP''': In scientific and academic contexts, BP (before present) or YBP (years before present) are often used. (''Present'' in this context conventionally refers to January{{nbsp}}1, 1950.) Write {{xt|3000 years{{nbsp}}BP}} or {{xt|3000{{nbsp}}YBP}} or {{xt|3000{{nbsp}}years before present}} but not forms such as {{!xt|3000 before present}} and {{!xt|3000 years before the present}}. If one of the abbreviated forms is used, link to ''[[Before present]]'' on first use: {{xt|The Jones artifact was dated to 4000{{nbsp}}[[before present|YBP]], the Smith artifact to 5000 YBP.}}
* {{anchor|Other_era_systems}}'''Other era systems''' may be appropriate in an article. In such cases, dates should be followed by a conversion to Dionysian (or vice versa) and the first instance should be linked: {{xt|Qasr-al-Khalifa was built in {{nobr|221{{nbsp}}[[Hijri year|AH]] (836{{nbsp}}CE)}}}}, or {{nobr|{{xt|in 836{{nbsp}}AD (221{{nbsp}}[[Hijri year|AH]])}}}}. 
** [[Astronomical year numbering]] follows the Common Era and does not require conversion, but the first instance of a non-positive year should still be linked: {{xt|The March equinox passed into Pisces in [[Astronomical year numbering|year{{nbsp}}−67]].}}

====Julian and Gregorian calendars====
{{shortcut|MOS:OSNS|MOS:JG}}
{{see also|Old Style and New Style dates}}

A date can be given in any appropriate calendar, as long as it is (at the minimum) given in the [[Julian calendar]] or the [[Gregorian calendar]] or both, as described below. For example, an article on the early [[history of Islam]] may give dates in both [[Islamic calendar|Islamic]] and Julian calendars. Where a calendar other than the Julian or Gregorian is used, the article must make this clear.
* Current events are dated using the Gregorian calendar.
* Dates of events in countries using the Gregorian calendar at that time are given in the Gregorian calendar. This includes some of the [[Gregorian calendar#Timeline|Continent of Europe from 1582]], the [[British Empire]] from 14{{nbsp}}September 1752, and Russia from 14{{nbsp}}February 1918 {{crossref|(see [[Adoption of the Gregorian calendar]])}}.
* Dates before 15{{nbsp}}October 1582 (when the Gregorian calendar was first adopted in some places) are normally given in the Julian calendar. The Julian day and month should not be converted to the Gregorian calendar, but the start of the [[Julian year (calendar)|Julian year]] should be assumed to be 1{{nbsp}}January {{crossref|(see below for more details)}}.
* Dates for Roman history before 45{{nbsp}}BC are given in the [[Roman calendar]], which was neither Julian nor Gregorian. When (rarely) the Julian equivalent is certain, it may be included.
* For dates in early Egyptian and Mesopotamian history, Julian or Gregorian equivalents are often uncertain. Follow the consensus of reliable sources, or indicate their divergence.

The dating method used should follow that used by reliable secondary sources (or if reliable sources disagree, that used most commonly, with an explanatory [[Help:Footnotes|footnote]]).

Where it's not obvious that a given date should be given in Julian alone or in Gregorian alone, consider giving both styles, for example by using {{tl|OldStyleDate}}. If a date appears without being specified as Old Style or New Style, tagging that date with {{tl|which calendar?}} will the page to [[:Category:Articles containing ambiguous dates]] for further attention.

If there is a need to mention [[Old Style and New Style dates|Old or New Style]] dates in an article (as in the [[Glorious Revolution]]), a footnote should be provided on the first usage, stating whether the New Style refers to a start of year adjustment or to the Gregorian calendar (it can mean either).

At some places and times, the new year began on a date other than 1{{nbsp}}January. For example, in England and its colonies until 1752, the year began on [[Annunciation Day]], 25{{nbsp}}March; {{crossref|see the [[New Year|New Year article]] for other styles}}. In writing about historical events, however, years should be assumed to have begun on 1{{nbsp}}January {{crossref|(see the example of the execution of Charles I in "[[Old Style and New Style dates#Differences in the start of the year|Differences in the start of the year]]")}}; if there is reason to use another start-of-year date, this should be noted.

====Ranges<span id="Date ranges"></span>====
{{anchors|Other date ranges|Dates of birth and death}}{{shortcut|MOS:DOB|MOS:OTHERDATE|MOS:DATERANGE}}
{{hatnote|Note: A change from a preference for two digits, to a preference for four digits, on the right side of ''year{{ndash}}year'' ranges was implemented in July 2016 per [[Special:Permalink/744053720#WP:DATERANGE ambiguity and stylistic concerns|this RFC]].}}<!-- For the record the change can be seen at https://en.wikipedia.org/?diff=744053720&oldid=744052603 -->
* Use a dash, or a word such as ''from'' or ''between'', but not both: {{xt|from 1881 to 1886}} (not {{!xt|{{nobr|from 1881{{ndash}}1886}}}});{{nbsp}} {{xt|between June{{nbsp}}1 and July{{nbsp}}3}} (not {{!xt|{{nobr|between June{{nbsp}}1{{snd}}July{{nbsp}}3}}}})
* A simple '''year{{ndash}}year''' range is written using an en dash (<code>&amp;ndash;</code> or {{tlx|ndash}}) not an em dash, hyphen or slash; this dash is {{em|unspaced}} (that is, with no space on either side); and the range's end year is usually given in full:
** {{xt|1881{{ndash}}1886}};{{nbsp}} {{xt|1881{{ndash}}1992}} (not {{!xt|1881{{ndash}}86}};{{nbsp}} {{nobr|{{!xt|1881{{snd}}1992}}}})
** {{hanging indent|text=Markup: <code>1881{{tl|ndash}}1886</code> or <code>1881&amp;ndash;1886</code>}}
** '''Two-digit ending years''' ({{xt|1881{{ndash}}82}}, but never {{!xt|1881{{ndash}}882}} or {{!xt|1881{{ndash}}2}}) {{em|may}} be used in any of the following cases: (1) two consecutive years; (2) infoboxes and tables where space is limited (using a single format consistently in any given table column); and (3) in certain topic areas if there is a very good reason, such as matching the established convention of reliable sources.
**The '''slash notation''' ({{xt|2005/2006}}) may be used to signify a fiscal year or other special period, if that convention is used in reliable sources.
* Other "simple" ranges use an {{em|unspaced}} en dash as well:
** '''day{{ndash}}day''': {{xt|5{{ndash}}7{{nbsp}}January 1979}};{{nbsp}} {{xt|January{{nbsp}}5{{ndash}}7, 1979}};{{nbsp}} {{xt|elections were held March 5{{ndash}}8}}.
** '''month{{ndash}}month''': {{xt|the 1940 peak period was May{{ndash}}July}};{{nbsp}} {{xt|the peak period was May{{ndash}}July{{nbsp}}1940}};{{nbsp}} (but {{xt|the peak period was {{nobr|May 1940{{snd}}July}} 1940}} uses a {{em|spaced}} en dash; {{crossref|see below}})
* If at least one item on either side of the en dash contains a space, then a {{em|spaced}} en dash ({{tlx|snd}}) is used. For example:
** '''between specific dates in different months''': {{xt|They travelled {{nobr|June{{nbsp}}3{{snd}}August{{nbsp}}18,}} 1952}};{{nbsp}} {{xt|They travelled 3{{nbsp}}June{{snd}}18{{nbsp}}August 1952}} 
** '''between dates in different years''':
*** {{xt|'''Charles Robert Darwin''' (12{{nbsp}}February {{nobr|1809{{snd}}19{{nbsp}}April}} 1882) was an English naturalist{{nbsp}}...}}
*** {{hanging indent|text=Markup: <code>12{{t|nbsp}}February 1809{{tl|snd}}19{{t|nbsp}}April 1882</code> or {{nowrap|<code>12&amp;nbsp;February 1809&amp;nbsp;&amp;ndash; 19&amp;nbsp;April 1882</code>}} }}
*** {{xt|'''Abraham Lincoln''' (February{{nbsp}}12, 1809{{snd}}April{{nbsp}}15, 1865) was the 16th President of{{nbsp}}...}} 
** '''between months in different years''': {{xt|The exception was in force August {{nobr|1892{{snd}}January}} 1903}};{{nbsp}} {{xt|The Ghent Incursion (March 1822{{snd}}January{{nbsp}}1, 1823) was ended by the New Year's Treaty}}
***{{hanging indent|text=Markup: <code>March 1822{{t|snd}}January{{t|nbsp}}1, 1823</code> or {{nowrap|<code>March 1822&amp;nbsp;&amp;ndash; January&amp;nbsp;1, 1823</code>}} }}
** Where '''era designations''', '''''circa''''' or '''other modifiers''' are present: {{nobr|{{xt|reigned 5 BC{{snd}}12 AD}}}};&nbsp; {{nobr|{{xt|reigned c. 1393{{snd}}1414}}}}. {{See below|Uncertain, incomplete, or approximate dates}}
{{shortcut|MOS:DATETOPRES}}{{anchors|Date range to present}}
* For ranges '''"to present"''', constructions such as {{nobr|{{xt|1982{{ndash}}present}}}} (with unspaced ndash), {{nobr|{{xt|January 1, 2011{{snd}}present}}}} (spaced ndash), or {{nobr|{{xt|January 2011{{snd}}present}}}} (spaced ndash) may be used, but other constructions may be more appropriate in prose {{crossref|(see {{section link||Statements likely to become outdated}})}}. In tables and infoboxes where space is limited, ''pres.'' may be used ({{xt|1982{{ndash}}pres.}}). Do not use incomplete-looking constructions such as {{nobr|{{!xt|1982{{ndash}}}}}} and {{nobr|{{!xt|1982{{ndash}}... }} .}}
* <p>For a '''person still living''': {{xt|'''Serena Williams''' (born September{{nbsp}}26, 1981) is a{{nbsp}}...}}, not {{!xt|(September{{nbsp}}26, 1981{{snd}})}} or {{!xt|(born on September{{nbsp}}26, 1981)}}.</p><p>Do not use <code>*</code> to indicate ''born''; use <code>b.</code> only where space is limited e.g. tables and infoboxes; use either <code>born</code> or <code>b.</code> consistently in any given table column.</p>
* <p>Where '''birthdate is unknown''': {{xt|'''John Smith''' (died May{{nbsp}}1, 1622)}} or {{xt|'''John Smith''' (died 1622)}}</p><p>Do not use <code>†</code> to indicate ''died''; use <code>d.</code> only where space is limited, with consistency within any given table column.</p>
* <p>An '''overnight period''' may be expressed using a slash between two contiguous dates: {{xt|the night raids of 30/31{{nbsp}}May 1942}} or {{xt|raids of 31{{nbsp}}May{{nbsp}}/ 1{{nbsp}}June 1942}}.</p><p>Or use an en dash: (unspaced) {{xt|raids of 30{{ndash}}31{{nbsp}}May 1942}};{{nbsp}} (spaced) {{xt|raids of {{nobr|31{{nbsp}}May{{snd}}1{{nbsp}}June}} 1942}}.</p>
* The {{tlx|Age}} template can keep ages current in infoboxes and so on:
** <code><nowiki>{{age|1989|7|23}}</nowiki></code> returns: {{xt|{{age|1989|7|23}}}}
** <code><nowiki>{{age|1989|7|23}}-year-old</nowiki></code> returns: {{xt|{{age|1989|7|23}}-year-old}}
** <code><nowiki>{{age|1989|7|23}} years old</nowiki></code> returns: {{xt|{{age|1989|7|23}} years old}}
* [[:Category:Date mathematics templates|Date mathematics templates]] are available for other age calculations.

====Uncertain, incomplete, or approximate dates====
<!--This section/anchor linked to from MOS:DATERANGE.-->
{{shortcut|MOS:APPROXDATE|MOS:CIRCA}}
* To indicate "around", "approximately", or "about", the use of the spaced, unitalicised form {{xt|c.{{nbsp}}1291}} (or the {{tlx|circa}} template) is preferred over {{!xt|circa}}, {{!xt|ca}}, {{!xt|ca.}}, {{!xt|around}}, {{!xt|approximately}}, or {{!xt|approx.}}:
** {{xt|At the birth of Roger Bacon (c. 1214){{nbsp}}...}}
** {{xt|'''John Sayer''' ({{circa}} 1750{{snd}}2{{nbsp}}October 1818){{nbsp}}...}}
** {{xt|the Igehalkid dynasty of Elam, {{circa|1400{{nbsp}}BC}}{{nbsp}}...}}
* Where both endpoints of a range are approximate, c. should appear before each date (the two-argument form of {{tlx|circa}} does this):
** {{xt|'''Dionysius Exiguus''' ({{circa}} 470{{snd}}{{circa}} 540){{nbsp}}...}} (not {{!xt|'''Dionysius Exiguus''' ({{circa}} 470{{snd}}540){{nbsp}}...}})
** {{xt|'''Rameses III''' (reigned {{circa|1180|1150{{nbsp}}BCE}}){{nbsp}}...}} (not {{!xt|'''Rameses III''' (reigned {{circa}} 1180{{snd}}1150{{nbsp}}BCE){{nbsp}}...}})
* Where birth/death limits have been inferred from known dates of activity:
** {{xt|'''Offa of Mercia''' (before 734{{snd}}26{{nbsp}}July 796){{nbsp}}...}}
** {{xt|'''Robert Menli Lyon''' (1789{{snd}}after 1863){{nbsp}}...}}
** {{xt|'''Ambrose Gwinnett Bierce''' (June 24, 1842{{snd}}after December 26, 1913){{nbsp}}...}}<!-- Relationship between "before/after" and "fl." needs to be clarified. -->
* When birth and death dates are unknown, but the person is known to have been active ("flourishing") during certain years, {{xt|fl.}}, <code><nowiki>[[Floruit|fl.]]</nowiki></code>, or {{tlx|fl.}} may be used:
** {{xt|'''Jacobus Flori''' ([[floruit|fl.]] 1571–1588) ...}}
: The linked forms should not be used on disambiguation pages, and "active" followed by the range is a better alternative for occupations not relating to the composition of works, whether it be musical, grammatical, historical, or any other such work.
* When a date is known to be either of two years (e.g. from a [[Regnal years of English monarchs|regnal]] or [[Hijri year|AH]] year conversion, or a known age at death):
** {{xt|'''Anne Smith''' (born 1912 or 1913; died 2013){{nbsp}}...}}
* Other forms of uncertainty should be expressed in words, either in article text or in a footnote: {{xt|April{{nbsp}}14, 1224 (unattested date)}}. Do not use a question mark ({{!xt|1291?}}), because it fails to communicate the nature of the uncertainty.
* Ranges in which {{xt|c.}}, {{xt|after}}, {{xt|fl.}} or similar forms appear{{mdashb}}whether on one or both sides{{mdashb}}employ a ''spaced'' endash (<code><nowiki>{{snd}}</nowiki></code>) and ideally a non-breaking space should follow very short modifiers such as {{xt|c.}} and {{xt|fl.}}. ''Examples'': {{nobr|1896{{snd}}after 1954}}, {{nobr|{{c.}}{{nbsp}}470{{snd}}{{c.}}{{nbsp}}540}}, {{nobr|{{c.|470|540}}}}. ''Markup:'' {{nobr|<code><nowiki>1896{{snd}}after 1954</nowiki></code>}}, {{nobr|<code><nowiki>{{c.}}{{nbsp}}470{{snd}}{{c.}}{{nbsp}}540</nowiki></code>}}, {{nobr|<code><nowiki>{{c.|470|540}}</nowiki></code>}}

===Times of day<span id="Time of day"></span>===
{{Shortcut|MOS:TIME}}
Context determines whether the [[12-hour clock|12-]] or [[24-hour clock|24-hour]] clock is used. In all cases, colons separate hours, minutes, and (where present) seconds, e.g. {{xt|1:38:09{{nbsp}}pm}} or {{xt|13:38:09}}. Use figures ({{xt|11{{nbsp}}a.m.}} or {{xt|12:45{{nbsp}}p.m.}}) rather than words ({{!xt|twelve forty-five p.m.}}).
* '''12-hour clock times''' end with lower-case {{xtn|a.m.}} or {{xtn|p.m.}}, or {{xtn|am}} or {{xtn|pm}}, preceded by a [[#Non-breaking spaces|non-breaking space]], e.g. {{xt|2:30{{nbsp}}p.m.}} or {{xt|2:30{{nbsp}}pm}} (markup: <code>2:30{{tl|nbsp}}p.m.</code> or <code>2:30{{tl|nbsp}}pm</code>), not {{!xt|2:30p.m.}} or {{!xt|2:30pm}}. Hours should not have a leading zero (e.g. {{xt|2:30{{nbsp}}p.m.}}, not {{!xt|02:30{{nbsp}}p.m.}}). Usually, use {{xt|noon}} and {{xt|midnight}} rather than {{!xt|12 pm}} and {{!xt|12 am}}; whether "midnight" refers to the start or the end of a date should be explicitly specified unless clear from the context. Where several times that are all a.m. or all p.m. appear in close proximity, then ''a.m.'' or ''p.m.'' need be given only once if there is no risk of confusion.
* '''24-hour clock times''' have no a.m., p.m., noon or midnight suffix, and include a colon ({{xt|15:30}} not {{!xt|1530}}). Hours under 10 should have a leading zero ({{xt|08:15}}). The time {{xt|00:00}} refers to midnight at the start of a date, {{xt|12:00}} to noon, and {{xt|24:00}} to midnight at the end of a date, but {{!xt|24}} should not be used for the first hour of the next day (e.g. use {{xt|00:10}} for ten minutes after midnight, not {{!xt|24:10}}).

'''<span id="timezones"></span>Time zones'''<!--fake section heading to reduce TOC clutter-->
{{shortcut|MOS:TIMEZONE}}Give dates and times appropriate to the [[time zone]] where an event took place. For example, the date of the [[attack on Pearl Harbor]] should be December{{nbsp}}7, 1941 (Hawaii time/{{zwsp}}date). Give priority to the place at which the event had its most significant effects; for example, if a hacker in Monaco attacked a Pentagon computer in the US, use the time zone for the Pentagon, where the attack had its effect. In some cases, the best solution may be to add the date and time in [[Coordinated Universal Time]] (UTC). For example:

{{in5}}{{xt|8{{nbsp}}p.m. [[Eastern Standard Time (North America)|Eastern Standard Time]] on January{{nbsp}}15, 2001 (01:00{{nbsp}}UTC, January{{nbsp}}16)}}

Alternatively, include just the [[UTC offset]]:

{{in5}}{{xt|21:00{{nbsp}}[[British Summer Time]] ([[UTC+1]]) on 27{{nbsp}}July 2012}}

Rarely, the time zone in which an event took place has since changed; for example, China to 1949 was divided into [[Historical time zones of China|five time zones]], whereas all of modern China is [[UTC+8]]. Similarly, the term "UTC" is not appropriate for dates before this system was adopted in 1960;<ref>{{cite book |id=CCTF/09-32 |title=Coordinated Universal Time (UTC) |date=June 2, 2009 |publisher=[[Bureau International des Poids et Mesures]] |page=3 |quote=This coordination began on January 1, 1960, and the resulting time scale began to be called informally 'Coordinated Universal Time.'&thinsp; |url= http://www.bipm.org/cc/CCTF/Allowed/18/CCTF_09-32_noteUTC.pdf |format=PDF |access-date=August 20, 2015}}</ref> [[Universal Time]] (UT) is the appropriate term for the mean time at the [[prime meridian (Greenwich)]] when it is unnecessary to specify the precise definition of the time scale. Be sure to show the UTC or offset appropriate to the clock time in use at the time of the event, not the modern time zone, if they differ.

<span id="Day, month and season names"></span><span id="Longer periods"></span><span id="Other periods"></span><span id="Other"></span>

===Days of the week===
* Days of the week are capitalized ({{xt|Sunday}}, {{xt|Wednesday}}). 
* Where space is limited (tables, infoboxes, etc.) an en dash may be used for a range ({{xt|Monday{{ndash}}Thursday}}).<!-- funny I don't remember any issue ever over use of abbreviations like Mon Tue Wed etc. -->

===Seasons of the year<span id="Seasons"></span>===
{{shortcut|MOS:SEASON}}
* Seasons are uncapitalized ({{xt|a hot summer}}) except when personified: {{xt|Old Man Winter's bleak greys relent as Spring begins to show her colors}}.
* Avoid the use of seasons to refer to a particular time of year ({{!xt|winter 1995}}) as such uses are ambiguous: the seasons are six months apart in the northern and southern hemispheres, and areas near the equator have only [[Wet season|wet]] and [[dry season]]s.
** Unambiguous alternatives include {{xt|early 1995}};{{nbsp}} {{xt|the first quarter of 1995}};{{nbsp}} {{xt|January to March 1995}};{{nbsp}} {{xt|spent the southern summer in Antarctica}}.
* Referring to a season by name is appropriate when it is part of a formal or conventional name or designation ({{xt|annual mid-winter festival}};{{nbsp}} {{xt|the autumn harvest}};{{nbsp}} {{xt|2018 Winter Olympics}};{{nbsp}} {{xt|''Times'' Fall Books Supplement}};{{nbsp}} {{xt|Details appeared in ''Quarterly Review'', Summer&nbsp;2015}};{{nbsp}} {{xt|The Court's winter term}}).

===Decades===
{{shortcut|MOS:DECADE}}
* To refer to a decade as a chronological period {{lang|la|per se}} (not with reference to a social era or cultural phenomenon), always use four digits as in {{xt|the{{nbsp}}1980s}}. Do not use {{!xt|the{{nbsp}}1980's}}, {{!xt|the{{nbsp}}1980{{nbh}}ies}}, or {{!xt|the{{nbsp}}1980s'}} (unless a possessive is actually meant).
** Prefixes should be hyphenated ({{xt|the{{nbsp}}mid{{nbh}}1980s}};{{nbsp}} {{xt|pre{{nbh}}1960s social attitudes}}).<!-- Non-breaking hyphens {{nbh}} are used in some examples to keep them from being fragmented over linebreaks here in MOS; that's not to say {{nbh}} ought to be used in "real life" in such situations. -->
* For a social era or cultural phenomenon associated with a particular decade:
** Two digits (with a preceding apostrophe) may be used as an alternative to four digits, {{em|but only if this is a well-established phrase seen in reliable sources}} ({{xt|the{{nbsp}}Roaring{{nbsp}}'20s}},{{nbsp}} {{xt|the{{nbsp}}Gay{{nbsp}}'90s}},{{nbsp}} {{xt|condemning the '60s counterculture}}, but {{xt|grew up in 1960s Boston, moving to Dallas in{{nbsp}}1971}}, and do not write {{!xt|the{{nbsp}}90's}};{{nbsp}} {{!xt|the{{nbsp}}90s}};{{nbsp}} or {{!xt|the{{nbsp}}90s'}}).
** A third alternative (where seen in reliable sources) is to spell the decade out, capitalized: {{xt|changing attitudes of the Sixties}}.

===Centuries and millennia<span id="centuries"></span><span id="millennia"></span>===
{{shortcut|MOS:CENTURY|MOS:MILLENNIUM}}
The sequence of numbered years in dates runs {{xt|...{{nbsp}}2{{nbsp}}BC, 1{{nbsp}}BC, 1{{nbsp}}AD, 2{{nbsp}}AD{{nbsp}}...}}; there is no "[[year zero]]".
* Treat the 1st century AD as years {{nobr|1{{ndash}}100}}, the 17th century as {{nobr|1601{{ndash}}1700}}, and the second millennium as {{nobr|1001{{ndash}}2000}}; similarly, the 1st century BC/BCE was {{nobr|100{{ndash}}1}} BC/BCE, the 17th century BC/BCE was {{nobr|1700{{ndash}}1601}} BC/BCE, and the second millennium {{nobr|2000{{ndash}}1001}} BC/BCE.
* Centuries and millennia are identified using either "Arabic" numerals ({{nobr|{{xt|the 18th century}}}}) or words ({{xt|the second millennium}}). When used adjectivally they contain a hyphen ({{xt|nineteenth-century painting}} or {{xt|{{nobr|19th-century}} painting}}). Do not use superscripts ({{!xt|19<sup>th</sup> century}}).
* Do not capitalize ({{!xt|the best Nineteenth-century paintings}};{{nbsp}} {{!xt|during the Nineteenth Century}}) 
* Do not use [[Roman numerals]] ({{!xt|XVIII{{nbsp}}century}}).
* {{xt|The 18th century}} refers to the period ({{nobr|1701{{ndash}}1800}}), while strictly {{!xt|the 1700s}} refers either to ({{nobr|1700{{ndash}}1799}}) or ({{nobr|1700{{ndash}}1709}})
** When using forms such as {{xt|the 1900s}}, ensure that there is no ambiguity as to whether the century or just its first decade is meant.
* {{crossref|See {{section link|WP:Manual of Style|En dashes}} for use of hyphens and dashes in obscure situations.}}

===Long periods of time<span id="Abbreviations for long periods of time"></span>===
* When the term is frequent, combine {{xtn|yr}}{{nbsp}}(years) or {{xtn|ya}}{{nbsp}}(years ago) with {{xtn|k}}{{nbsp}}(thousand): {{xtn|kya}}, {{xtn|kyr}}; {{xtn|M}}{{nbsp}}(million): {{xtn|Mya}}, {{xtn|Myr}}; and {{xtn|b}}{{nbsp}}([[Long and short scales|short-scale]] billion): {{xtn|bya}}, {{xtn|byr}}. {{Crossref|(See {{section link|Year|Abbreviations yr and ya}} for more information.)}}
* In academic contexts, [[International System of Units|SI]] annus-based units are often used: {{xtn|ka}}{{nbsp}}(kiloannus), {{xtn|Ma}}{{nbsp}}(megaannus), and {{xtn|Ga}}{{nbsp}}(gigaannus). {{Crossref|(See {{section link|Year|SI prefix multipliers}} for more information.)}}
* Show the meaning parenthetically, and consider linking to the appropriate section of the [[Year]] article {{crossref|(see links above)}} on first occurrence and where the use is a standalone topic of interest. In source quotations, use square brackets: {{xt|"a measured Libby radiocarbon date of 35.1{{nbsp}}mya [million years ago] required calibration ..."}}

==Numbers==
===Numbers as figures or words===
{{shortcut|MOS:NUMERAL|MOS:SPELL09}}
{{crossref|Information on specific situations is scattered elsewhere on this page.}}

'''Generally, in article text:'''
:{{see also| Template:Spellnum per MOS}}
* Integers from zero to nine are spelled out in words.
* Integers greater than nine {{em|expressible in one or two words}} may be expressed either in numerals or in words ({{xt|16}} or {{xt|sixteen}}, {{xt|84}} or {{nobr|{{xt|eighty-four}}}}, {{xt|200}} or {{nobr|{{xt|two hundred}}}}). When written as words, numbers between 21 and 99 are hyphenated (including when part of a larger number): {{nobr|{{xt|fifty-six}}}} or {{nobr|{{xt|fifty-six thousand}}}} but {{xt|five{{nbsp}}hundred}} or {{xt|five{{nbsp}}thousand}}.
* Other numbers are given in numerals ({{xt|3.75}}, {{xt|544}}) or in forms such as {{xt|21{{nbsp}}million}}. Markup: {{nowrap|<code><nowiki>21{{nbsp}}million</nowiki></code>}}
** ''Billion'' and ''trillion'' are understood to represent their [[Long and short scales|short-scale]] values of 10<sup>9</sup>{{nbsp}}(1,000,000,000) and 10<sup>12</sup>{{nbsp}}(1,000,000,000,000), respectively. Keep this in mind when translating articles from non-English or older sources.
** {{xt|M}} (unspaced, capitalized) or {{xt|bn}} (unspaced) respectively may be used for "million" or "billion" after a number, when the word has been spelled out at the first occurrence ({{xt|She received &pound;70{{nbsp}}million and her son &pound;10M}}).<!-- This needs to be coordinated with text in units tables re nonuse of M (for 1000) MM, etc. -->
** SI prefixes and symbols, such as {{xtn|mega-}}{{nbsp}}({{xtn|M}}), {{xtn|giga-}}{{nbsp}}({{xtn|G}}) and {{xtn|tera-}}{{nbsp}}({{xtn|T}}), should be used only with units of measure as appropriate to the field, and not to express large quantities in other contexts. Examples of misuse: {{!xt|In a population of 1.3G{{nbsp}}people, 300{{nbsp}}megadeaths would be expected.}}
** Sometimes, the [[Wikipedia:Manual of Style#National varieties of English|variety of English]] used in an article may suggest the use of a numbering system other than the Western thousands-based system. For example, the [[South Asian numbering system]] is conventionally used for certain things (especially monetary amounts) in [[South Asian English]]. This is discouraged in Wikipedia articles by {{section link|WP:Manual of Style#Opportunities for commonality}}.
*** When it is done anyway, for contextually important reasons, link the first spelled-out instance of each quantity (e.g. <code><nowiki>[[crore]]</nowiki></code>, which yields: [[crore]]). If no instances are spelled out, provide a note after the first instance, directing the reader to the article about the numbering system.
*** Provide a conversion to Western numbers for the first instance of each quantity (the templates {{tlx|lakh}}, {{tlx|crore}}, and {{tlx|lakh crore}} may be used for this purpose), and provide conversions for subsequent instances if they do not overwhelm the content of the article. For example, write {{xt|three [[crore]] (thirty million)}}. When converting a currency amount, use the exchange rate that applied at the time being written about; the {{tlx|INRConvert}} template can be used for this purpose.
*** Group digits in Western thousands-based style (e.g., {{xt|30,000,000}}; not {{!xt|3,00,00,000}}); {{crossref|see {{section link||Delimiting (grouping of digits)}}, below}}.
*** The variety of English does not uniquely determine the method of numbering in an article. Other considerations&nbsp;– such as conventions used in mathematics, science, and engineering&nbsp;– may also apply. The choice and order of formats and conversions is a matter of editorial discretion and consensus at the article.

{{anchor|Numeral notes}}{{shortcut|MOS:NUMNOTES}}
'''Notes and exceptions:'''

* Avoid beginning a sentence with a figure:
** Use: {{nowrap|{{xt|There were many matches''';''' 23 ended in a draw.}}}} Or: {{nowrap|{{xt|There were many matches'''.''' Twenty-three ended in a draw.}}}}
** Not: {{!xt|There were many matches'''.''' 23 ended in a draw.}}
** Use: {{xt|No elections were held in 1945 and 1950.}}
** Not: {{nowrap|{{!xt|1945 and 1950 had no elections.}}}} (Nor: {{nowrap|{{!xt|Nineteen forty-five and 1950 had no elections}} {{ndash}}}} comparable numbers should be both written in words or both in figures.)
** Opening a sentence with a proper name or technical term that begins with a numeral can usually be avoided by rewording:
*** Prefer: {{xt|Typically, 1-naphthylamine is synthesized via the Feldenshlager–Glockenspiel process.}} Or: {{xt|Feldenshlager{{ndash}}Glockenspiel is the process typically used in the synthesis of 1-naphthylamine.}}
*** Avoid: {{!xt|1-Naphthylamine is typically synthesized via the Feldenshlager{{ndash}}Glockenspiel process.}}
* In tables and infoboxes, quantities are expressed in figures ({{xt|Years in office:{{nbsp}}5}}); but numbers within a table's explanatory text and comments follow the general rule.
* Numbers in mathematical formulae are never spelled out ({{nobr|{{xt|3 < π < 22/7}}}}, not {{nobr|{{!xt|three < π < 22 sevenths}}}}).
* Sport scores and vote tallies should be given as figures, even if in the zero-to-nine range ({{xt|a 25–7 victory}}; and {{xt|passed with 7 ayes, 2 nays, and 1 abstention}}).
* Comparable quantities should be all spelled out or all in figures, even if one of the numbers would normally be written differently: {{xt|five cats and thirty-two dogs}}, or {{xt|5 cats and 32 dogs}}, not {{!xt|five cats and 32 dogs}}
* Adjacent quantities not comparable should usually be in {{em|different formats:}} {{nobr|{{xt|twelve 90-minute volumes}}}} or {{nobr|{{xt|12 ninety-minute volumes}}}}, not {{nobr|{{!xt|12 90-minute volumes}}}} or {{nobr|{{!xt|twelve ninety-minute volumes}}}}.
** Avoid awkward juxtapositions: {{xt|On February 25, 2011, twenty-one more were chosen}}, not {{nobr|{{!xt|On February 25, 2011, 21 more were chosen}}}}.
* Sometimes figures and words carry different meanings; for example, {{xt|Every locker except one was searched}} implies there is a single exception (without specifying which), while {{xt|Every locker except{{nbsp}}1 was searched}} means that only locker number{{nbsp}}1 was not searched.
* Proper names, technical terms, and the like are never altered: {{xt|[[10 Downing Street]]}},{{nbsp}} {{xt|[[Nine Inch Nails]]}},{{nbsp}} {{xt|[[Channel 8 (Thailand)|Channel 8]]}},{{nbsp}} {{xt|''[[Seven Samurai]]''}},{{nbsp}} {{xt|''[[The Sixth Sense]]''}},{{nbsp}} {{xt|[[Chanel No.&nbsp;5]]}},{{nbsp}} {{xt|[[Fourth Estate]]}},{{nbsp}} {{xt|''[[The Third Man]]''}},{{nbsp}} {{xt|[[Second Coming]]}},{{nbsp}} {{xt|[[First Amendment]]}},{{nbsp}} {{xt|''[[Zero Hour!]]''}},{{nbsp}} {{xt|[[Less Than Zero (song)|Less Than Zero]] }}
* Figures as figures: Use a figure when the figure itself (its [[glyph]], shape, etc.) is meant: {{xt|a figure-8 pattern}}; {{xt|in the shape of the numeral ''6''}}. {{crossref|(See {{section link|WP:Manual of Style/Text formatting#Words as words}}.)}}
* Only figures are used with unit {{em|symbols}} ({{xt|2 min}} not {{!xt|two min}}), but figures or words may be used with unit {{em|names}} ({{xt|2 minutes}} or {{xt|two minutes}}), within the guidelines above. {{Crossref|(See also table: [[#General guidelines on unit names and symbols|General guidelines on unit names and symbols]].)}}
{{shortcut|MOS:ORDINAL|MOS:1ST}}<!-- Positioned before (rather than after) section in question to avoid crash of shortcut boxes when sections are short. -->

===Ordinals===
{{anchor|1st|1ST}}
* For guidance on choosing between e.g. {{xt|15th}} and {{xt|fifteenth}}, see {{section link||Numbers as figures or words}}.
* Use two-letter suffixes as ordinal indicators: {{xt|1st, 2nd, 3rd, 4th}} and so on ({{xt|2nd{{nbsp}}Battalion}} not {{!xt|2d{{nbsp}}Battalion}}). Do not superscript ({{!xt|123<sup>rd</sup>}}).
* Do not use a dot ({{!xt|.}}) or the ordinal mark ({{!xt|&#186;}}) to indicate ordinals.
* [[Regnal number]]s are normally written with [[Roman numeral]]s (without suffix, e.g. {{xt|Elizabeth II}} not {{!xt|Elizabeth IInd}} or {{!xt|Elizabeth 2nd}}).

===Number ranges===
{{shortcut|MOS:NUMRANGE}}
As with date ranges {{crossref|(see [[#Date ranges|above]])}}, number ranges in general, such as page ranges, should state the full value of both the beginning and end of the range, with an [[MOS:DASH|en dash]] between, e.g. {{xt|pp.{{nbsp}}1902{{ndash}}1911}} or {{xt|entries{{nbsp}}342{{ndash}}349}}.
Forms such as {{xtn|1901{{ndash}}11}} and {{xtn|342{{ndash}}9}} may be used where space is limited (such as in tables and infoboxes), or where a [[WP:CITEVAR|citation style]] formally requires it. (As usual, quotations are not changed.)

===Singular versus plural===

* Nouns following [[Simple fractions|simple fractions]] are singular ({{xt|took {{frac|4}} dose}};{{nbsp}} {{xt|net change was &minus;{{frac|2}} point}};{{nbsp}} {{xt|{{frac|3|2}} dose}}).
* Nouns following [[mixed number]]s are plural ({{xt|1{{frac|1|2}} doses}};{{nbsp}} {{xt|another 4{{frac|3|4}} miles}}).
* Nouns following the lone, unsigned digit ''1'' are singular, but those following other decimal numbers (i.e. base-10 numbers not involving fractions) are plural ({{xt|increased 0.7 percentage points}};{{nbsp}} {{xt|365.25&nbsp;days}};{{nbsp}} {{xt|paid 5 dollars per work hour, 1 dollar per travel hour, 0 dollars per standby hour}};{{nbsp}} {{xt|increased by 1&nbsp;point}} but {{xt|net change +1&nbsp;points}};{{nbsp}} {{xt|net change &minus;1&nbsp;points}};{{nbsp}} {{xt|net change 1.0&nbsp;points}}).
* The same rules apply to numbers given in words ({{xt|one dose}};{{nbsp}} {{xt|one and one-half doses}};{{nbsp}} {{xt|zero dollars}};{{nbsp}} {{xt|net change of negative one points}}).

===Fractions and ratios<span id="Fractions"></span>===
{{shortcut|MOS:FRAC|MOS:RATIO}}
* Spelled-out fractions are hyphenated: {{xt|seven-eighths}}.
* Where numerator and denominator can each be expressed in one word, a fraction is usually [[Fractions#Pronunciation and spelling|spelled out]] (e.g. {{xt|a two-thirds majority}}; {{nbsp}}{{xt|moved one-quarter mile}}); use figures if a fraction appears with a symbol (e.g. {{xt|{{frac|1|4}}{{nbsp}}mi}}{{snd}}markup: <code>{{tlx|frac|1|4}}&amp;nbsp;mi</code>, not {{!xt|a quarter of a mi}} or {{!xt|one-quarter mi}}). A common exception is a series of values: {{xt|The distances were {{frac|1|1|4}}, {{frac|2|3}} and {{frac|1|2}} mile, respectively}}.
* [[Mixed numbers]] are usually given in figures, unspaced (not {{!xt|Fellini's film ''8{{nbsp}}{{frac|1|2}}''}} or {{!xt|''8-{{frac|1|2}}''}} but {{xt|Fellini's film ''{{frac|8|1|2}}''}}{{snd}}markup: <code><nowiki>{{frac|8|1|2}}</nowiki></code>). In any case the integer and fractional parts should be consistent (not {{!xt|nine and{{nbsp}}{{frac|1|2}}}}).
* Metric (SI) measurements generally use decimals, not fractions ({{xt|5.25{{nbsp}}mm}}, not {{!xt|5{{frac|1|4}}{{nbsp}}mm}}).
* Non-metric (imperial and US customary) measurements may use fractions or decimals ({{xt|5{{frac|1|4}}{{nbsp}}inches}};{{nbsp}}{{xt|5.25{{nbsp}}inches}}); the practice of reliable sources should be followed, and within-article consistency is desirable.
* In science and mathematics articles, mixed numbers are rarely used (use {{xt|{{sfrac|4|3}} the original}} rather than {{!xt|1{{sfrac|1|3}} times the original voltage}}). The use of {{tlx|frac}} [[Wikipedia:Manual of Style/Mathematics#Fractions|is discouraged]] in favor of one of these styles:
** <math>\textstyle\frac{1}{2}</math>{{snd}}markup: <code><[[WP:MATH|math]]>\textstyle\frac{1}{2}<nowiki></math></nowiki></code>
** {{xt|{{sfrac|1|2}}}}{{snd}}markup: {{tlx|sfrac|1|2}}
** {{xt|1/2}}{{snd}}markup: <code>1/2</code>
* Do not use special characters such as {{!xt|&frac12;}} (deprecated markup: <s><code>&amp;frac12;</code></s> or <s><code>&amp;#189;</code></s>).
* Ordinal suffixes such as {{xtn|-th}} should not be used with fractions expressed in figures (not {{!xt|each US state has 1/50th of the [[United States Senate|Senate's]] votes}}; {{!xt|1/8th mile}}, but {{xt|one-fiftieth of the [[United States Senate|Senate's]] votes}}; {{xt|1/8 mile}}; {{xt|one-eighth mile}}).
*Dimensionless ratios (i.e. those without accompanying units) are given by placing a colon between integers, or placing ''to'' between numbers-as-words: {{ xt|favored by a 3:1 ratio}} or {{nobr|{{ xt|a three-to-one ratio}}}}, not {{nobr|{{!xt|a 3/1 ratio}}}} or {{nobr|{{!xt|a 3&ndash;1 ratio}}.}} 
**Use a colon (spaced) when one or more decimal points is present {{nobr|({{ xt|a 3.5&nbsp;:&nbsp;1 ratio}}{{snd}}markup:}} {{nobr|<code>a 3.5&amp;nbsp;:&amp;nbsp;1 ratio</code>).}} 
**Do not use the colon form where units are involved ({{!xt|dissolve using a {{nobr|3 ml : 1 g ratio}}}}){{mdashb}}instead see ''ratios'' section of table at [[#Unit names and symbols|§&nbsp;Unit names and symbols]], below.''

===Decimals<span id="Decimal points"></span>===
{{shortcut|WP:DECIMAL|MOS:DECIMAL}}
* A period/full point (<code>.</code>){{snd}}{{em|never}} a comma{{snd}}is used as the decimal point ({{xt|6.57}}, not {{!xt|6,57}}).
* Numbers between −1 and +1 require a leading zero ({{xt|0.02}}, not {{!xt|.02}}); exceptions are sporting performance averages ({{xt|.430 [[batting average (baseball)|batting average]]}}) and commonly used terms such as {{xt|.22{{nbsp}}caliber}}.
* Indicate repeating digits with an [[Vinculum (symbol)|overbar]] e.g. {{nowrap|<code><nowiki>14.31{{overline|28}}</nowiki></code>}} gives {{xt|14.31{{overline|28}}}}. (Consider explaining this notation on first use.) Do not write e.g. {{nobr|{{!xt|14.31(28)}}}} because it resembles [[#Uncertainty|notation for uncertainty]].

===Grouping of digits===
<span id="Delimiting (grouping of digits)"></span><span id="Grouping of digits"></span>
{{Technical reasons|Project:Digits|the Microsoft Research project|Project Digits}}
{{shortcut|WP:DIGITS|MOS:DIGITS}}
* Digits should be grouped and separated either by commas or by narrow gaps ({{em|never}} a period/full point).
*; Grouping with commas
*: Left of the decimal point, five or more digits are grouped into threes separated by commas (e.g. &nbsp;{{xt|12,200}}, &nbsp;{{xt|255,200&nbsp;km}}, &nbsp;{{xt|8,274,527th}}, &nbsp;{{xt|{{frac|86,400}}}}).
*: Numbers with exactly four digits left of the decimal point may optionally be grouped (either &nbsp;{{xt|1,250}} &nbsp;or &nbsp;{{xt|1250}}), provided that this is consistent within each article.
*: When commas are used left of the decimal point, digits right of the decimal point are not grouped (i.e. should be given as an unbroken string).
*: Markup: {{tlc|[[Help:Parser functions|formatnum:]]}} produces this formatting.
*; Grouping with narrow gaps
*: Digits are grouped both sides of the decimal point (e.g. &nbsp;{{xt|{{val|6543210.123456}}}}, &nbsp;{{xt|{{val|520.01234|u=degC}}}}, &nbsp;{{xt|{{sfrac|{{val|101325}}|760}}}}).
*: Digits are generally grouped into threes. Right of the decimal point, {{em|usual}} practice is to have a final group of four in preference to leaving an "orphaned" digit at the end ({{xt|{{val|99.1234567}}}}, but {{xt|{{gaps|99.123|456|7}}}} would also be acceptable). In mathematics-oriented articles long strings may be grouped into fives (e.g. &nbsp;{{xt|{{gaps|3.14159|26535|89793|23846|...}}}}).
*: This style is especially recommended for articles related to science, technology, engineering or mathematics.
*: Markup: Templates {{tlx|val}} or {{tlx|gaps}} may be used to produce this formatting. Note that use of {{em|any}} space character as a separator<!--Word included here on purpose, for in-page searching.--> in numbers, including non-breaking space, is problematic for [[screen reader]]s. {{crossref|(See {{section link||Non-breaking spaces}}.)}} Screen readers read out each {{em|group}} of digits as separate numbers (e.g. &nbsp;<code>30&amp;thinsp;000</code>&nbsp; is read as "thirty zero zero zero".)
* Delimiting style should be consistent throughout a given article.
** Either use commas or narrow gaps, but not both in the same article.
** Either group the thousands in a four-digit number or do not, but not mixed use in the same article.
** However, grouping by threes and fives may coexist.
* An exception is made for four-digit page numbers or four-digit calendar years. These should never be grouped (not &nbsp;{{!xt|sailed in 1,492}}, &nbsp;though &nbsp;{{xt|dynasty collapsed around 10,400&nbsp;BC}} &nbsp;or &nbsp;{{xt|by {{val|13727|u=AD}}, Vega will be the northern pole star}}).

===Percentages===
{{shortcut|MOS:PERCENT|WP:PERCENT|WP:%}}
* In the body of non-scientific/non-technical articles, {{xtn|percent}} (American English) or {{xtn|per cent}} (British English) are commonly used: {{xt|10 percent}}; {{xt|ten percent}}; {{xt|4.5 per cent}}. Ranges are written {{xt|ten to twelve per cent}} or {{xt|ten to twelve percent}}, not {{!xt|ten{{ndash}}twelve per cent}} or {{!xt|ten to twelve{{nbsp}}%}}.
* In the body of scientific/{{zwsp}}technical articles, and in {{em|tables and infoboxes}} of any article, the symbol <code>%</code> (unspaced) is more common: {{xt|3%}}, not {{!xt|3{{nbsp}}%}} or {{!xt|three{{nbsp}}%}}. Ranges: {{xt|10{{ndash}}12%}}, not {{!xt|10%{{ndash}}12%}} or {{nobr|{{!xt|10 to 12%}}}}.
* When expressing the difference between two percentages, do not confuse a percentage change with a change in [[percentage point]]s.

===Scientific and engineering notation<span id="Scientific notation, engineering notation, and uncertainty"></span>===
* [[Scientific notation]] always has a single nonzero digit to the left of the point: not {{!xt|{{val|60.22|e=22}}}}, but {{xt|{{val|6.022|e=23}}}}. 
* [[Engineering notation]] is similar, but adjusted so that the exponent is a multiple of three: {{xt|{{val|602.2|e=21}}}}.
* Avoid mixing scientific and engineering notations ({{!xt|A {{val|2.23|e=2|u=m2}} region covered by {{val|234.0|e=6|u=grains of sand}}}}). 
* In a table column (or other presentation) in which all values can be expressed with a single power of 10, consider giving e.g. {{xt|{{e|7}}}} once in the column header, and omitting it in the individual entries. (Markup: <code><nowiki>{{e|7}}</nowiki></code>)
* In both notations, the number of digits indicates the precision. For example, {{xt|{{val|5|e=3}}}} means rounded to the nearest thousand; {{xt|{{val|5.0|e=3}}}} to the nearest hundred; {{xt|{{val|5.00|e=3}}}} to the nearest ten; and {{xt|{{val|5.000|e=3}}}} to the nearest unit.

Markup: {{tlx|val}} and {{tlx|e}} may be used to format exponential notation.

===Uncertainty and rounding <span id="Uncertainty"></span> <span id="Large numbers"></span>===
{{shortcut|MOS:UNCERTAINTY|MOS:LARGENUM}}
* Where explicit uncertainty information (such as a [[margin of error]]) is available and appropriate for inclusion, it may be written in various ways:
** {{xt|(1.534 ± 0.035) × 10<sup>23</sup> m}} 
** {{xt|12.34{{nbsp}}m<sup>2</sup> ± 5%}} (not used with scientific notation)
** {{xt|15.34 {{su|p=+0.43|b=−0.23}} × 10<sup>23</sup> m}} 
** {{xt|1.604(48) × 10<sup>−4</sup> J}} (equivalent to {{xt|(1.604 ± 0.048) × 10<sup>−4</sup> J}}){{efn|1=The number in parentheses in a construction like {{xt|1.604(48) × 10<sup>−4</sup> J}} is the numerical value of the standard uncertainty referred to the corresponding last digits of the quoted result.<ref>{{cite web |url= http://www.physics.nist.gov/cgi-bin/cuu/Info/Constants/definitions.html |title=Fundamental Physical Constants: Standard Uncertainty and Relative Standard Uncertainty |work=The NIST Reference on Constants, Units, and Uncertainty |date=June 25, 2015<!--Last updated, according to https://physics.nist.gov/cuu/Constants/bibliography.html --> |publisher=US [[National Institute of Standards and Technology]] |access-date=December 12, 2017}}</ref>}}
** {{xt|Polls estimated Jones's share of the vote would be 55 percent, give or take about 3 percent}}
** Markup: {{tlx|+-}}, {{tlx|su}}, and {{tlx|val}} may be used to format uncertainties.
* Where explicit {{em|uncertainty is unavailable}} (or is unimportant for the article's purposes) round to an appropriate number of [[significant digit]]s; the precision presented should usually be conservative. Precise values (often given in sources for formal or matter-of-record reasons) should be used only where stable and appropriate to the context, or significant in themselves for some special reason.
** {{xt|The speed of light is defined to be 299,792,458{{nbsp}}m/s}}
** {{em|but}} {{xt|Particle velocities eventually reached almost two-thirds the 300-million-metre-per-second speed of light.}}
** {{xt|checks worth $250 (equivalent to $1,800 in 2016)}} (not {{!xt|$1,845.38 in 2016}})
** {{xt|The city's 1920 population was 10,000}} (not {{!xt|population was 9,996}}{{snd}}an official figure unlikely to be accurate at full precision)
** {{em|but}} {{xt|The town was ineligible because its official census figure (9,996) fell short of the statutory minimum of ten thousand }} (unusual case in which the full-precision official figure is truly informative)
** {{xt| The accident killed 337 passengers and crew, and 21 people on the ground }} (likely that accurate and precise figures were determined)
** {{xt| At least 800 persons died in the ensuing mudslides }} (unlikely that any precise number can be accurate, even if an official figure is issued)
** {{em|or}} {{xt| Officials listed 835 deaths, but the Red Cross said dozens more may have gone unreported }} (in reporting conflicting information, give detail sufficient to make the contrast intelligible)
** {{xt|The jury's award was $8.5{{nbsp}}million}} (not {{!xt|$8,462,247.63}}). {{xt|The appeals court reduced this to $3,000,001 (one dollar in actual damages, the remainder in punitive damages).}}
* The number of decimal places should be consistent within a list or context ({{xt|The response rates were 41.0 and 47.4 percent, respectively}}, not {{!xt|41 and 47.4 percent}}), unless different precisions are actually intended.
* It may sometimes be appropriate to note the {{em|lack}} of uncertainty information, especially where such information is normally provided and necessary for full interpretation of the figures supplied.
** {{xt|A local newspaper poll predicted 52 percent of the vote would go to Smith, but did not include information on the uncertainty of this estimate}}
* The {{tlx|undue precision}} template may be added to figures appearing to be overprecise.
* Avoid using "approximately", "about", and similar terms with figures that have merely been approximated or rounded in a normal and expected way, unless the reader might otherwise be misled.
** {{xt|The tallest player was 6 feet 3 inches}} ({{nobr|not {{!xt|... about 6 feet 3 inches}}}}{{snd}}heights are conventionally reported only to the nearest inch, even though greater precision may be available in principle)<!-- Please, no lectures about SI – if you can give a parallel metric example please do so. -->
** {{em|but}} {{xt|The witness said the assailant was about 5 feet 8 inches tall}} ("about" because here the precise value is unknown, with substantial uncertainty)
* The reader may be assumed to interpret large round numbers ({{xt|100,000 troops}}) as approximations. Writing a quantity in words ({{xt|one hundred thousand troops}}) can further emphasize its approximate nature.
* {{crossref|See {{section link||Unit conversions}} below for precision issues when converting units.}}

===Non-[[radix|base]]-10 notations===
{{shortcut|MOS:BASE|MOS:RADIX|MOS:BINARY|MOS:HEX}}
* In computer-related articles, use the prefix <code>0x</code> for hexadecimal, <code>0</code> for octal, and <code>0b</code> for binary, unless there is a strong reason to use some other notation.{{efn|1=The <code>0x</code> and <code>0</code> prefixes, but not <code>0b</code>, are borrowed from the [[C (programming language)|C programming language]].}} Explain these prefixes in the article's introduction or on first use.
* In all other articles, use <code>&lt;sub></code> to create subscripts: {{xt|137<sub>9</sub>}}, {{xt|201<sub>3</sub>}}. Markup: <code><nowiki>137<sub>9</sub></nowiki></code>, <code><nowiki>201<sub>3</sub></nowiki></code>
* For bases above 10, use symbols conventional for that base (as seen in reliable sources) e.g. for [[base 16]] use {{nobr|0{{ndash}}9 and A{{ndash}}F}}.

===Mathematical formulae===
{{Main|Wikipedia:Manual of Style/Mathematics}}
For the display of a mathematical formula, there are multiple options, covered in detail at {{section link|WP:Manual of Style/Mathematics#Typesetting of mathematical formulae}}. One uses special MediaWiki {{tag|math}} markup using [[LaTeX]] syntax, which is capable of complex formulae; the other relies on conventionalized [[HTML]] formatting of simple formulae.

On the user end, the {{tag|math|o}} markup is displayed as a [[Portable Network Graphics|PNG]] image by default. Logged-in users can optionally have it rendered in [[MathML]], or in HTML (via [[MathJax]]); detailed instructions are at [[Help:Displaying a formula]].

[[Wikipedia:Manual of Style#Section headings|Do not put {{tag|math|o}} markup in headings]]; it is an [[Wikipedia:Manual of Style/Accessibility#Images|accessibility problem]].

==Units of measurement==
{{Shortcut|WP:UNIT|WP:UNITS|WP:METRIC|WP:MEASUREMENT}}

===Unit choice and order===

Quantities are typically expressed using an appropriate "primary unit", displayed first, followed, when appropriate, by a conversion in parentheses e.g. {{xt|{{convert|200|km|mi}}}}. For details on when and how to provide a conversion, see the section {{section link||Unit conversions}}. The choice of primary units depends on the circumstances, and should respect the principle of "[[Wikipedia:Strong national ties|strong national ties]]", where applicable:

* In '''non-scientific articles relating to the United States''', the primary units are [[United States customary units|US customary]], e.g. {{xt|97{{nbsp}}pounds (44{{nbsp}}kg)}}.
* In '''non-scientific articles relating to the United Kingdom''', the primary units for most quantities are metric or other internationally used units,{{efn|1=If there is disagreement about the primary units used in a UK-related article, discuss the matter on the article talk-page or at [[Wikipedia talk:Manual of Style/Dates and numbers]] ([[WT:MOSNUM]]). If consensus cannot be reached, refer to historically stable versions of the article and retain the units used in these as the primary units. Also note the [[Metrication in the UK#Newspapers|style guides]] of British publications (e.g. [https://web.archive.org/web/20110918050646/http://www.timesonline.co.uk/tol/tools_and_services/specials/style_guide/article986731.ece ''The Times''], under "Metric").}} except that:
** UK engineering-related articles, including those on bridges and tunnels, generally use the system of units that the topic was [[engineering drawing|drawn up]] in (but road distances are given in imperial units, with a metric conversion – see next bullet);
** the primary units for distance/{{zwsp}}length, speed and fuel consumption are miles, miles per hour, and miles per imperial gallon (except for short distances or lengths, where miles are too large for practical use);
** the primary units for personal height and weight are feet{{zwsp}}/inches and stones/{{zwsp}}pounds;
** imperial pints are used for quantities of draught beer/{{zwsp}}cider and bottled milk;
* In '''all other articles''', the primary units chosen will be [[International System of Units|SI]] units, [[Non-SI units mentioned in the SI|non-SI units officially accepted for use with the SI]], or such other units as are conventional in reliable-source discussions of the article topic (such as [[revolutions per minute]] (rpm) for [[rotational speed]], [[hand (unit)|hand]]s for heights of horses, et cetera).

{{em|Special considerations:}}
* Quantities set via definition (as opposed to measured quantities) should be given first in the units used in the definition, even if this makes the structure of presentation inconsistent: {{xt|During metrification, the speed limit was changed from 30{{nbsp}}mph (48{{nbsp}}km/h) to 50{{nbsp}}km/h (31{{nbsp}}mph)}}.
** Or use ''about'' to emphasize which is the statutory, exact value: {{xt|...from 30{{nbsp}}mph (about 48{{nbsp}}km/h) to 50{{nbsp}}km/h (about 31{{nbsp}}mph)}}. 
* Nominal quantities (e.g. {{xt|2{{nbsp}}×{{nbsp}}4}} [[Lumber#North American softwoods|lumber]]) require consideration of whether the article is concerned with the item's actual dimensions or merely with its function. In some cases, the nominal quantity may suffice; in others it may be necessary to give the nominal size (often in non-SI units), the actual size in non-SI units, and the actual size in SI units.
* Whenever a conversion is used, ensure that the precision of the converted quantity in the article is comparable to the precision of the value given by the source {{crossref|(see {{section link||Unit conversions}})}}.
* Where the article's primary units differ from the units given in the source, the {{tlx|convert}} template's <code>|order=flip</code> flag can be used; this causes the {{em|original}} unit to be shown as secondary in the article, and the {{em|converted}} unit to be shown as primary: <code><nowiki>{{convert|200|mi|km|order=flip}}</nowiki></code> &rarr; {{xt|The two cities are {{convert|200|mi|km|order=flip}} apart.}}

===Unit conversions===
{{shortcut|MOS:CONVERSIONS|WP:MOSCONVERSIONS}}
Where English-speaking countries use different units for the same quantity, provide a conversion in parentheses: {{xt|the Mississippi River is {{convert|2320|mi|km|0}} long}}; {{xt|the Murray River is {{convert|2508|km|mi|0}} long}}. But in science-related articles, supplying such conversion is not required unless there is some special reason to do so.
* Where an [[imperial unit]] is not part of the [[United States customary units|US customary system]], or vice versa{{snd}}and in particular, where those systems give a single term different definitions{{snd}}a double conversion may be appropriate: {{xt|Rosie weighed {{convert|80|kg|lb stlb}}}} (markup: <code><nowiki>{{convert|80|kg|lb stlb}}</nowiki></code>); {{xt|{{nobr|The car}} had a fuel economy of {{convert|5|L/100km|mpgus mpgimp|abbr=on}}}} (markup: <code><nowiki>{{convert|5|L/100km|mpgus mpgimp|abbr=on}}</nowiki></code>).
* Generally, conversions to and from metric units and US or imperial units should be provided, except:
** When inserting a conversion would make a common or linked expression awkward ({{xt|The four-minute mile}}).
** When units are part of the subject of a topic{{snd}}nautical miles in articles about the history of nautical law ({{xt|5 nautical miles}}), [[International System of Units|SI]] units in scientific articles ({{xt|a 600-kilometer asteroid}}), yards in articles about American football{{snd}}it can be excessive to provide conversions every time a unit occurs. It might be best to note that this topic will use the units (possibly giving the conversion factor to another familiar unit in a parenthetical note or a footnote), and link the first occurrence of each unit but not give a conversion every time it occurs.
* Converted quantity values should use a {{em|level of precision}} similar to that of the source quantity value, so {{xt|the Moon is 380,000{{nbsp}}kilometres (240,000{{nbsp}}mi) from Earth}}, not {{!xt|(236,121{{nbsp}}mi)}}. Small numbers may need to be converted to a range where rounding would cause a significant distortion, so {{xt|one mile (1–2{{nbsp}}km)}}, not {{!xt|one mile (2{{nbsp}}km)}}. Be careful especially when your source has already converted from the units you're now converting back to. This may be evidenced by multiples of common conversion factors in the data, such as 160 km (from 100 miles). {{crossref|See [[false precision]].}}
* [[:Category:Conversion templates|'''Conversion templates''']] can be used to convert and format many common units, including {{tlx|convert}}, which includes non-breaking spaces. 
* In a '''direct quotation''', always retain the source units. Any conversions can be supplied either in the quote itself (in square brackets, following the original measurement) or in a footnote. {{crossref|See [[Wikipedia:Footnotes|footnoting]] and [[Wikipedia:Citing sources|citing sources]].}}
* {{tlx|Units attention}} may be added to articles needing general attention regarding choice of units and unit conversions.
* Avoid [[Wikipedia:Edit warring|edit-warring]] over unit conversions, or performing mass conversions from one unit style to another across many articles; [[Wikipedia:Sanctions|sanctions]] may apply.{{efn|See, e.g., [[Wikipedia:General sanctions/Units in the United Kingdom]].}}

===Unit names and symbols===
{{shortcut|MOS:UNITNAMES|MOS:UNITSYMBOLS|WP:UNITNAMES|WP:UNITSYMBOLS}}
:{{em|Definitions:}}
:* Examples of '''unit names''': foot, metre, kilometre, (meter, kilometer US).
:* Examples of '''unit symbols''': ft, m, km.

* Unit names and symbols should follow the practice of reliable sources.
* In prose, unit names should be given in full if used only a few times, but symbols may be used when a unit (especially one with a long name) is used repeatedly, after spelling out the first use (e.g. {{xt|Up to 15 kilograms of filler is used for a batch of 250{{nbsp}}kg}}).
** Exception: Certain units<!--<<perhaps identify these in table of specific units elsewhere on this page--> are generally represented by their symbols (e.g. {{xt|&deg;C}} rather than {{!xt|degrees Celsius}}) even on first use, though their unit names may be used for emphasis or clarity ({{xt|conversion of degrees Celsius to degrees Fahrenheit}}).
** Exception: Consider using ''inches'' (but not ''in.'') in place of ''in'' where the latter might be misread as a preposition<!--can someone supply an example? (if no one can think of one after a while, then maybe this exception never actually arises)-->{{mdashb}}but not where the value is followed by a parenthesized conversion e.g. {{xt|bolts 5&nbsp;in (12.7&nbsp;cm) long}}, or is part of such a conversion ({{xt|bolts 12.7&nbsp;cm (5&nbsp;in) long}}).
* Where space is limited, such as in tables, infoboxes, parenthetical notes, and mathematical formulas, unit symbols are preferred.
* Units unfamiliar to general readers should be presented as a name{{ndash}}symbol pair on first use, linking the unit name ({{xt|Energies were originally 2.3 [[megaelectronvolt]]s (MeV), but were eventually 6{{nbsp}}MeV}}).
* Ranges use unspaced en dash ({{tlx|ndash}}) if only one unit symbol is used at the end (e.g. {{xt|5.9{{ndash}}6.3{{nbsp}}kg}}), and spaced en dash ({{tlx|snd}}) if two symbols are used (e.g. {{xt|3{{nbsp}}μm{{snd}}1{{nbsp}}mm}}); ranges in prose may be specified using either unit symbol or unit names, and units may be stated either after both numerical values or after the last (all acceptable: {{nobr|{{xt|from 5.9 to 6.3 kilograms}}}}; {{nobr|{{xt|from 5.9 kilograms to 6.3 kilograms}}}}; {{nobr|{{xt|from 5.9 to 6.3{{nbsp}}kg}}}}; {{nobr|{{xt|from 5.9{{nbsp}}kg to 6.3{{nbsp}}kg}}}}).
* Length{{ndash}}width, length{{ndash}}width{{ndash}}height and similar dimensions may be separated by the multiplication sign (<code>×</code> or <code>&amp;times;</code>) or the word <code>by</code>.
** With the multiplication sign, each number should be followed by a unit name or symbol (if appropriate):
*** {{xt|1 m × 3 m × 6 m}}, not {{nobr| {{!xt|1 × 3 × 6 m}}}}, {{!xt|(1 × 3 × 6) m}}, nor {{nobr| {{!xt|1 × 3 × 6 m<sup>3</sup>}} }}
*** {{xt|a metal plate 1 ft × 3 ft × 0.25 in}}
***{{xt|a railroad easement 10 ft × 2.5 mi}}
** The {{xtn|×}} symbol is preceded by a space (preferably non-breaking), and followed by a space (which may also be non-breaking in short constructions).
** With {{xtn|by}}, the unit need be given only once if it is the same for all values: {{nobr| {{xt|1 by 3 by 6 metres}} }} or {{nobr| {{xt|1 by 3 by 6 m}} }}
** The unspaced letter {{xt|x}} may be used in common terms such as {{xt|[[4x4]]}}.

{| class="wikitable"
|+ {{vanchor|General guidelines on use of units}}
|-
! {{Vert header|<small>Aspect</small>}}
! Guideline<!--this column picks up whatever width is left over from other columns-->
! style="width:40px;"<!--undersized width specification means that column size is set by widest word/nobreaked phrase in column contents-->| [[File:Yes check.svg|11px|link=|alt=]] Acceptable
! style="width:40px;"<!--undersized width specification means that column size is set by widest word/nobreaked phrase in column contents-->|[[File:X mark.svg|11px|link=|alt=]] Unacceptable
|-
|rowspan=7 {{Vert header|va=middle|<small>'''Unit names and symbols'''</small>}}
|Except as listed in the {{section link||Specific units}} table below, unit {{em|symbols}} are uncapi{{shy}}tal{{shy}}ized unless they are derived from a proper name, in which case the first letter (of the base unit symbol, not of any prefix) is capitalized.{{efn|1=These definitions are consistent with all units of measure mentioned in the ''SI Brochure''<ref name="SI Brochure" /> and with all units of measure catalogued in [[European units of measurement directives|EU directive 80/181/EEC]].<ref>{{cite web |title=Council Directive of 20 December 1979 on the approximation of the laws of the Member States relating to units of measurement |id=80/181/EEC (Document 01980L0181-20090527) |work=Eur-Lex.Europa.eu |publisher=[[European Union]] |date=2017 |orig-year=1979 |url=http://eur-lex.europa.eu/legal-content/EN/TXT/?qid=1397640809938&uri=CELEX:01980L0181-20090527 |access-date=December 12, 2017}}</ref>}}
| {{ xt|8 kg}}<br/>{{ xt|100 kPa}}
| {{!xt|8 Kg}}<br/>{{!xt|100 kpa}}
|-
|Unit symbols are undotted.
|{{ xt|38 cm of rope }}
|{{!xt|38 cm<big>.</big> of rope}}
|-
|Unit {{em|names}} are given in lower case except: where any word would be capital{{shy}}ized, or where otherwise specified in the SI brochure<ref name="SI Brochure">{{cite book |title=SI Brochure: The International System of Units (SI) |edition=8th |orig-year=2006 |year=2014 |publisher=[[Bureau International des Poids et Mesures]] |url= http://www.bipm.org/en/publications/si-brochure/ |section=Chapter 4: Non-SI units accepted for use with the SI, and units based on fundamental constants (contd.) |section-url= http://www.bipm.org/en/publications/si-brochure/chapter4.html |access-date=August 20, 2015}} Tables 6, 7, 8, and 9 give additional guidance on non-SI units.</ref> or this Manual of Style.
|{{plainlist|
* {{ xt|He walked several miles.}}
* {{ xt|Miles of trenches were dug.}}
}}
|{{!xt|A Gallon equals 4{{nbsp}}Quarts.}}
|-
|The spelling of certain unit names (some of which are listed in {{section link||Specific units}}, below) varies with the [[Wikipedia:Manual of Style#National varieties of English|variety of English followed by the article]].
|
|
|-
|rowspan=2 | Write unit names and symbols in upright ([[Roman type|{{sic|hide=y|roman}}]]) type, except where emphasizing in context.
| {{ xt|10{{nbsp}}m}}<br/>{{ xt|29 kilograms}}
| {{!xt|10{{nbsp}}{{em|m}}}}<br/>{{!xt|29 {{em|kilograms}}}}
|-
| {{ xt|Thus each two-liter jug contained only two {{em|quarts}}.}}
|
|-
|Do not use precomposed unit symbol characters.
|
|<code>㎓</code>, <code>㎦</code>
|-
|rowspan=8 {{Vert header|va=middle|<small>'''Numeric values'''</small>}}<!-- WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF RULES -->
|Do not spell out numbers before unit {{em|symbols}}{{nbsp}}...
|{{ xt|12{{nbsp}}min}}
|{{!xt|twelve{{nbsp}}min}}
|-
|...{{nbsp}}but words {{em|or}} figures may be used with unit {{em|names}}.
|{{plainlist|
* {{ xt|twelve minutes}}
* {{ xt|12 minutes}}
}}
|
|-
| A value with no accompanying unit is usually given in figures.
| {{ xt|Set the pointer to 5.}}
| {{!xt|Set the pointer to five.}}
|-
| Use a non-breaking space ({{tlx|nbsp}} or <code>&amp;nbsp;</code>) between a number and a unit {{em|symbol}}, or use {{tlx|nowrap}}{{nbsp}}...
| {{xt|29{{nbsp}}kg}}<br/>(markup: <code>29&amp;nbsp;kg</code> or {{nowr|<code><nowiki>{{nowrap|29 kg}}</nowiki></code>}})
| style="vertical-align: top"| {{!xt|29kg}}
|-
| ... though with certain symbols ''no'' space is used (see "Specific{{nbsp}}units" table below){{nbsp}}...
| {{nobr|{{xt|23&deg;}} {{xt|47&prime;}} {{xt|22&Prime;}} }}
| {{nobr|{{!xt|23{{nbsp}}&deg;}} {{!xt|47{{nbsp}}&prime;}} {{!xt|22{{nbsp}}&Prime;}} }}
|-
| ... and a normal space is used between a number and a unit {{em|name}}.
| {{xt|29{{nbsp}}kilograms}}<br/>(markup: <code>29&nbsp;kilograms</code>)
|
|-
|To form a value and a unit {{em|name}} into a compound adjective use a hyphen or hyphens{{nbsp}}...
|{{plainlist|
* {{ xt|a five-day holiday}}
* {{ xt|a five-cubic-foot box}}
* {{ xt|a 10-centimeter blade}}
}}
|
|-
|... but a non-breaking space (never hyphen) separates a value and unit {{em|symbol}}.
|{{plainlist|
* {{ xt|a blade 10 cm long}}<!-- What about "a 10 cm bridge"? -->
}}
| {{!xt|a 10-cm blade}}
|-
|rowspan=5 {{Vert header|va=middle|<small>'''Plurals'''</small>}}<!-- WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF RULES -->
|[[International System of Units|SI]] unit {{em|names}} are pluralized by adding the appropriate {{xt|-s}} or {{xt|-es}} suffix{{nbsp}}...<!--Not that it matters much, but I'm having trouble finding an SI unit taking -es. -->
|{{ xt|1 ohm}}; {{xt|10 ohms}}<!--What's an example with "-es"?-->
|
|-
| ... except for these irregular forms.
| {{ xt|1 henry}}; {{ xt|10 henries}}<br/>{{ xt|1 hertz}}; {{ xt|10 hertz}}<br/>{{ xt|1 lux}}; {{xt|10 lux}}<br/>{{ xt|1 siemens}}; {{xt|10 siemens}}
|{{!xt|10 henrys }}<br/>{{!xt|10 hertzes}}<br/>{{!xt|10 luxes}}<br/>{{nbsp}}<!--dummy fourth line keeps content lined up with prior column-->
|-
|rowspan=2 | Some non-SI units have irregular plurals.<!-- This is meant to be placeholder which perhaps someone can expand (though foot, feet is the only example I can think of at the moment). -->
| {{ xt|1 foot}}; {{xt|10 feet}}
| {{!xt|10 foots}}
|-
| {{ xt|1 stratum}}; {{xt|10 strata}} (unusual) <!-- Rare, but is occasionally used as a measurement unit; can't think of any others, didn't find any in searching. -->
| {{!xt|10 stratums}}
|-
|Unit {{em|symbols}} (in any system) are identical in singular and plural.
|{{plainlist|
* {{nobr|{{xt|grew from 1 in to 2 in}} }}
* {{nobr|{{xt|grew from 1 inch to 2 inches}} }}
* {{nobr|{{xt|grew from one to two inches}} }}
}}
|{{nobr|{{!xt|grew from 1 in to 2 ins}} }}
|-
|rowspan=5 {{Vert header|va=middle|<small>'''Powers'''</small>}}<!-- WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF RULES -->
|Format exponents using <nowiki><sup></nowiki>, not special characters.
|{{xt|km<sup>2</sup>}}<br/>(markup: <code>km&lt;sup>2&lt;/sup></code>)
|{{!xt|km&#178;}}<br/>(<code>km&amp;#178;</code>)
|-
|Or use {{xtn|squared}} or {{xtn|cubed}} ({{em|after}} the unit being modified).
|rowspan=2|{{xt|ten metres per second squared}}
|{{!xt|ten metres per squared second}}
|-
|rowspan=2| For areas or volumes only, {{xtn|square}} or {{xtn|cubic}} may be used ({{em|before}} the unit being modified).
|{{!xt|ten metres per square second}}
|-
|{{xt|tons per square mile}}
|
|-
| {{xtn|sq}} or {{xtn|cu}} may be used with US customary or imperial units, but not with [[International System of Units|SI]] units.
| {{ xt|15{{nbsp}}sq{{nbsp}}mi}}<br/>{{ xt|3{{nbsp}}cu{{nbsp}}ft }}
| {{!xt|15{{nbsp}}sq{{nbsp}}km}}<br/>{{!xt|3{{nbsp}}cu{{nbsp}}m }}
|-
|rowspan=4 {{Vert header|va=middle|<small>'''Products'''</small>}}<!-- WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF RULES -->
|Indicate a product of unit {{em|names}} with either a hyphen or a space.
|{{plainlist|
* {{ xt|foot-pound}}
* {{ xt|foot pound}}
}}
|{{plainlist|
* {{!xt|footpound}}
* {{!xt|foot&sdot;pound}}
}}
|-
|Indicate a product of unit {{em|symbols}} with <code>&amp;[[dot operator|sdot]];</code> or <code>&amp;[[non-breaking space|nbsp]];</code>.
|{{plainlist|1= <!-- 1= is needed because text below contains = -->
* {{ xt|ms}} = millisecond
* {{ xt|m&sdot;s}} or {{xt|m{{nbsp}}s}} = metre-second
}}
|
|-
|{{em|Exception:}} In some topic areas, such as power engineer{{shy}}ing, certain products take neither space nor <code>&amp;sdot;</code>. Follow the practice of reliable sources in the article's topic area.
|{{plainlist|
* [[watt hour|{{xt|Wh}}]], [[volt ampere|{{xt|VA}}]], [[ampere hour|{{xt|Ah}}]]
* {{xt|kWh}}, {{xt|MVA}}, {{xt|GAh}}
}}
|
|-
|To pluralize a product of unit {{em|names}}, pluralize only the final unit. (Unit {{em|symbols}} are never pluralized.)
|{{ xt|ten foot-pounds}}
|{{!xt|ten feet-pounds}}
|-
|rowspan=7 {{Vert header|va=middle|<small>'''Ratios, rates, densities'''</small>}}<!-- WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF RULES -->
|Indicate a ratio of unit {{em|names}} with {{xtn|per}}.
|{{ xt|meter per second}}
|{{!xt|meter/second}}
|-
|rowspan=2|Indicate a ratio of unit {{em|symbols}} with a forward slash (<code>/</code>), followed by either a single symbol or a parenthesized product of symbols{{snd}}do not use multiple slashes. Or use{{nbsp}}<sup>&minus;1</sup>,{{nbsp}}<sup>&minus;2</sup>, etc.
|{{plainlist|
* {{ xt|metre per second}}
* {{ xt|m/s}}
* {{ xt|m&sdot;s<sup>&minus;1</sup>}}
}}
|{{plainlist|
* {{!xt|mps}}
}}
|-
|{{plainlist|
* {{ xt|kg/(m&sdot;s)}}
* {{ xt|kg&sdot;m<sup>&minus;1</sup>&sdot;s<sup>&minus;1</sup>}}
}}
|{{plainlist|
* {{!xt|kg/m&sdot;s}}
* {{!xt|kg/m/s}}
}}
|-
|To pluralize a ratio of unit {{em|names}}, pluralize only the numerator unit. (Unit {{em|symbols}} are never pluralized.)
|{{plainlist|
* {{nowrap|{{xt|ten newton-metres per second}} }}<!-- Nowrap on longest value in column establishes minimum col width. -->
* {{xt|10 N&sdot;m/s}}
}}
|
|-
|Some of the special forms used in the imperial and US customary systems are shown here{{nbsp}}...
|{{plainlist|1= <!-- 1= is needed because text below contains = -->
* {{ xt|mph}} = miles per hour
* {{ xt|mpg}} = miles per gallon
* {{ xt|psi}} = [[pound (force)|pound]]s per square inch
}}
|
|-
|rowspan=2| ... but only the slash or negative exponent notations are used with SI (and other metric) units.
| {{plainlist|
* {{ xt|g/m<sup>2</sup>}}
* {{ xt|g&sdot;m<sup>&minus;2</sup>}}
}}
| {{!xt|gsm}}
|-
| {{plainlist|
* {{ xt|km/h}}
* {{ xt|km&sdot;h<sup>&minus;1</sup>}}
}}
| {{!xt|kph}}
|-
|rowspan=4 {{Vert header|va=middle|<small>'''Prefixes'''</small>}}<!-- WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF RULES -->
|Prefixes should not be separated by a space or hyphen.
|{{ xt|25 kilopascals}}
|{{plainlist|
* {{!xt|25 kilo pascals}}
* {{!xt|25 kilo-pascals}}
}}
|-
| Prefixes are added without contraction,<!--give example--> except as shown here:
| {{ xt|kilohm }}<br/>{{ xt|megohm }}<br/>{{xt|hectare}}
| {{!xt|kiloohm}}<br/>{{!xt|megaohm}}<br/>{{!xt|hectoare}}
|-
|The {{xtn|centi-}}, {{xtn|deci-}}, {{xtn|deca-}}, and {{xtn|hecto-}} prefixes should generally be avoided; exceptions include<!--Check SI source; also, since we're supposed to follow the units in sources, don't those control anyway?--> centimetre, decibel, hectolitre, hectare, and hectopascal.
|{{plainlist|
* {{ xt|100 metres}}
* {{ xt|0.1 km}}
}}
|{{!xt|1 hectometre}}
|-
| Do not use [[wikt:M#Number|{{!xt|M}}]] for 10<sup>3</sup>, {{!xt|MM}} for 10<sup>6</sup>, or {{!xt|B}} for 10<sup>9</sup> (except as noted elsewhere on this page for {{xtn|M}} and {{xtn|B}}, e.g. [[#Currencies and monetary values|for monetary values]])
| {{ xt|3 km }}<br/>{{ xt|8 MW }}<br/>{{ xt|125 GeV}}
| {{!xt|3 Mm }}<br/>{{!xt|8 MMW }}<br/>{{!xt|125 BeV}}
|-
|rowspan=4 {{Vert header|va=middle|<small>'''Mixed units'''</small>}}<!-- ← Use <br /> to make this column as narrow as possible.--><!-- WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF RULES -->
|rowspan=2| Mixed units are traditionally used with the imperial and US customary systems{{nbsp}}...
|{{anchor|Mixed units}}<!-- ← This anchor should go at the portion of the row which is vertically highest. -->{{plainlist|
* {{xt|a wall 1 ft 1 in thick}}
* {{xt|a wall 1 foot 1 inch thick }}
* {{xt|a man 6 feet 2 inches tall}}
* {{xt|a 6-foot 2-inch man}}
* {{xt|a 6 ft 2 in man}}
}}
|{{plainlist|
* {{nobr| {{!xt|1 ft{{hsp}}, 1 in }} (no comma) }}
* {{!xt|1 foot{{hsp}}, 1 inch}}
* {{!xt|a man 6 foot 2 tall}}
* {{!xt|a 6-foot 2 man}}
* {{nbsp}}
}}
|-
|{{plainlist|
* {{xt|1 US fl pt 8 oz}}
* {{xt|1 US fl pt 8 US fl oz}}
}}
|
|-
|... and in expressing time durations{{nbsp}}...
|{{plainlist|
* {{xt|1:30:07}}
* {{xt|1:30}}{{thinsp}}<ref group="note">Only use this format if it is clear from the context whether this means hours and minutes (H:MM) or minutes and seconds (M:SS).</ref>
* {{xt|{{nobr|1 h 30 min 7 s}}}}
* {{xt|{{nobr|01<sup>h</sup> 30<sup>m</sup> 07<sup>s</sup>}}}}{{thinsp}}{{refn|group=note|This format is used in astronomy (see the IAU Style Manual<ref>{{cite book |title=IAU Style Manual |first=G. A. |last=Wilkins |chapter=5.14 Time and angle |page=S23 |date=1989 |url= https://www.iau.org/static/publications/stylemanual1989.pdf |format=PDF |publisher=[[International Astronomical Union]] |access-date=12 December 2017}}</ref> for details).}}
}}
||{{plainlist|
* {{!xt|{{nobr|1:30&prime;07&Prime;}}}}
* {{!xt|{{nobr|1 hr 30 min 7 sec}}}}
* {{!xt|{{nobr|1 h 30 m 7 s}}}}
}}
|-
|... but are not normally used in SI.
|{{plainlist|
* {{xt|1.33 m }}
* {{xt|133 cm }}
}}
|{{!xt|1 m 33 cm}}
|}
{{em|Note to table:}}
{{reflist | group=note}}

===Specific units===
* The following table lists only units that need special attention.
* The ''SI Brochure''<ref name="SI Brochure" /> should be consulted for guidance on use of other SI and non-SI units.

{|class="wikitable"
|+ Guidelines on specific units
|-
! {{Vert header|<small>Group</small>}}
! style="width:40px;"<!--undersized width specification means that column size is set by widest word/nobreaked phrase in column contents-->| Name
! style="width:40px;"<!--undersized width specification means that column size is set by widest word/nobreaked phrase in column contents-->| Symbol
! Comment<!--this column picks up whatever width is left over from other columns-->
|-
| rowspan = 8 {{Vert header|va=middle|<small>'''Length, speed'''</small>}}<!-- WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF UNITS -->
| {{plainlist|
*inch
*foot
}}
| {{plainlist|
* {{ xt|in}}
* {{ xt|ft}}
}}
| Do not use <code>&amp;prime;</code>{{nbsp}}({{!xt|&prime;}}), <code>&amp;Prime;</code>{{nbsp}}({{!xt|&Prime;}}), apostrophe{{nbsp}}({{!xt|'}}) or quote{{nbsp}}({{!xt|"}}).
|-
| foot per second
| {{ xt|ft/s}} ({{em|not}} {{!xt|fps}})
|
|-
| [[Hand (unit)|hand]]
| {{xt|h}} or {{ xt|hh}}
| Equal to 4 inches; used in measurement of horses. A dot may be followed by additional inches e.g. {{nobr|{{xt|16.2 hh}}}} indicates {{nobr|16 hands 2 inches.}}
|-
| knot
| {{xt|kn}} ({{em|not}} {{!xt| [[kilotonne|kt]]}} or {{!xt|[[kilonewton|kN]]}})<!--not sure how to resolve the conflicting coloration desiderata-->
|
|-
| {{plainlist|
* metre
* meter {{em|(US)}}
}}
| {{xt|m}}
|
|-
| micron
| {{xt|&mu;m}} ({{em|not}} {{!xt|&mu;}})
| Markup: <code>&amp;mu;m</code>{{nbsp}} Link to [[micrometre]] (for which micron is a synonym) on first use.
|-
| [[astronomical unit]]
| {{xt|au}}<br />{{nobr| ({{em|not}} {{!xt|A.U.}}, {{!xt|ua}}) }}
| The preferred option is {{xt|au}}. Articles that already use {{xtn|AU}} may switch to au or continue with AU; seek consensus on the talk page.
|-
|{{plainlist|
* mile
* miles per hour
* nautical mile
}}
|{{plainlist|
*{{xt|mi}}
*{{xt|mph}}<!-- not ever mi/h??-->
*{{nobr| {{xt|nmi}} or {{xt|NM}} {{nobr|({{em|not}} {{!xt|[[nanometre|nm]]}} or {{!xt|M}})}} }}
}}
| In nautical and aeronautical contexts use {{xt|statute mile}}<!-- ← Should this be an entry in the table? --> rather than mile to avoid confusion with nautical mile.
|-
| rowspan = 6 {{Vert header|va=middle|<small>'''Volume, flow'''</small>}}<!-- WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF UNITS -->
| rowspan = 2 | {{plainlist|
* cubic centimetre
* {{nobr| cubic centimeter {{em|(US)}} }}
}}
| {{xt|cm<sup>3</sup>}}
| Markup: <code><nowiki>cm<sup>3</sup></nowiki></code>
|-
| {{xt|cc}}
| Non-SI abbreviation used for certain [[engine displacement]]s; link to [[Cubic centimetre]] on first use.<!-- I wonder if this can't be better coordinated with mpg, mph etc in earlier table. -->
|-
|{{plainlist|
*imperial fluid ounce
*imperial pint
*imperial quart
*imperial gallon
*US fluid ounce
*US fluid pint
*US fluid quart
*US gallon
}}
|{{plainlist|
* {{xt|imp fl oz}}
* {{xt|imp pt}}
* {{xt|imp qt}}
* {{xt|imp gal}}
* {{xt|US fl oz}}
* {{xt|US fl pt}}
* {{xt|US fl qt}}
* {{xt|US gal}}
}}
| {{xtn|US}} or {{xtn|imperial}} (or {{xtn|imp}}) must be specified; {{xtn|fluid}} or {{xtn|fl}} must be specified for fluid ounces and US units, except with gallon. (Without {{xtn|fluid}}, [[ounce]] is ambiguous{{snd}}versus avoirdupois ounce or troy ounce{{snd}}and US [[pint]] or US [[quart]] are ambiguous{{snd}}versus US dry pint or US dry quart.)
|-
| cubic foot
| {{xt|cu ft}} ({{em|not}} {{!xt|cf}})
| Write {{xt|five million cubic feet}}, {{xt|5,000,000{{nbsp}}cu{{nbsp}}ft}}, or {{xt|{{val|5|e=6|u=cuft}}}}, not {{!xt|5{{nbsp}}MCF}}.
|-
| {{nobr| cubic foot per second }}
| {{xt|cu ft/s}} ({{em|not}} {{!xt|cfs}})
|
|-
| {{plainlist|
* litre
* liter {{em|(US)}}
}}
| {{xt|l}} or {{xt|L}}
| The symbol l (lowercase "el") in isolation (i.e. outside forms as ml) is easily mistaken for the digit{{nbsp}}1 or the capital letter{{nbsp}}I{{nbsp}}("eye").
|-
| rowspan=6 {{Vert header|va=middle|<small>'''Mass, force, density, pressure'''</small>}}<!-- WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF UNITS -->
|{{plainlist|
* [[long ton]]
* [[short ton]]
}}
|{{plainlist|
*{{xt|long ton}}
*{{xt|short ton}}
}}
| Spell out in full.
|-
| {{nobr| pound per square inch }}
| {{xt|psi}}
|
|-
| {{plainlist|
* [[tonne]]
* [[tonne|metric ton]] {{em|(US)}}
}}
| {{xt|t}} {{nobr|({{em|not}} {{!xt|mt}} or {{!xt|MT}})}}
|
|-
| troy ounce
| {{xt|oz t}}
| rowspan=2 | {{xtn|t}} or {{xtn|troy}} must be specified. Articles about precious metals, black powder, and gemstones<!-- Is this list complete? --> should always specify whether ounces and pounds are [[Avoirdupois|avoirdupois]] or [[Troy weight|troy]].
|-
| troy pound
| {{xt|lb t}}
|-
| [[Carat (mass)|carat]]
| {{xt|carat}}
| Used to express masses of gemstones and pearls.
|-
| {{Vert header|va=middle|<small>'''Purity'''</small>}}<!-- WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF UNITS -->
| [[Carat (purity)|carat or karat]]
| {{xt|k}} or {{xt|Kt}}
| A measure of purity for gold alloys. (Do not confuse with the unit of mass with the same spelling.)
|-
| rowspan=3 {{Vert header|va=middle|<small>'''Time'''</small>}}
| {{plainlist|
*second
*minute
*hour
}}
| {{plainlist|
*{{xt|s}}
*{{xt|min}}
*{{xt|h}}
}}
|Do not use <code>&amp;prime;</code>{{nbsp}}({{!xt|&prime;}}), <code>&amp;Prime;</code>{{nbsp}}({{!xt|&Prime;}}), apostrophe{{nbsp}}({{!xt|'}}) or quote{{nbsp}}({{!xt|"}}) for minutes or seconds. See also the hours–minutes–seconds formats for time durations described in the [[#Mixed units|Unit names and symbols table]].
|-
| rowspan=2|year
| {{xt|a}}
| Use {{xtn|a}} only with an [[SI annus|SI prefix multiplier]] ({{xt|a rock formation 540{{nbsp}}Ma{{nbsp}}old}}, not {{!xt|Life expectancy rose to 60 a}}).
|-
| {{xt|y}} or {{xt|yr}}
| {{crossref|See {{section link||Long periods of time}} for all affected units.}}
|-
| rowspan=4 <!-- WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF UNITS -->{{Vert header|va=middle|<small>'''Information, data'''</small>}}
| bit
| {{xt|bit}} {{nobr|({{em|not}} {{!xt|b}} or {{!xt|B}})}}
| rowspan=4 | {{crossref|See also {{section link||Quantities of bytes and bits}}, below.}} Do not confuse bit/second or byte/second with [[baud|baud (Bd)]].
|-
| byte
| {{nobr| {{xt|B}} or {{xt|byte}} ({{em|not}} {{!xt|b}} or {{!xt|[[octet (computing)|o]]}}) }}
|-
| bit per second
| {{xt|bit/s}} ({{em|not}} {{!xt|bps}}, {{!xt|b/s}})
|-
| byte per second
| {{xt|B/s}} or {{xt|byte/s}} {{nobr|({{em|not}} {{!xt|Bps}}, {{!xt|bps}}, {{!xt|b/s}})}}
|-
| rowspan = 4 {{Vert header|va=middle|<small>'''Angle'''</small>}}<!-- - - - WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF UNITS - - - -->
|-
| [[arcminute]]
| {{xt|&prime;}}
| Markup: <code>&amp;prime;</code>{{nbsp}} ([[prime (symbol)|prime&nbsp;&prime;]] not apostrophe/{{zwsp}}single quote{{nbsp}}{{!xt|'}}). {{nobr|No space ({{xt|47&prime;}}, not {{!xt|47{{nbsp}}&prime;}}). }}
|-
| [[arcsecond]]
| {{xt|&Prime;}}
| Markup: <code>&amp;Prime;</code>{{nbsp}} ([[double prime (symbol)|double prime&nbsp;&Prime;]] not double-quote{{nbsp}}{{!xt|"}}). {{nobr|No space ({{xt|22&Prime;}}, not {{!xt|22{{nbsp}}&Prime;}}). }}
|-
| degree
| {{xt|&deg;}}
| Markup: <code>&amp;deg;</code> (degree &deg; not [[masculine ordinal]] {{!xt|&#186;}} or [[ring (diacritic)|ring]]&nbsp;{{thinsp}}{{!xt|&#778;}}{{hsp}}<!--<<hsp is needed to prevent crash between ring and closing paren, at least on some browsers-->). {{nobr|No space ({{xt|23&deg;}}, not {{!xt|23{{nbsp}}&deg;}}). }}
|-
| rowspan = 3 {{Vert header|va=middle|<small>'''Temperature'''</small>}}<!-- - - - WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF UNITS - - - -->
| degree Fahrenheit
| {{xt|&deg;F}} ({{em|not}} {{!xt|F}})
| rowspan = 2 | Markup: <code>&amp;deg;</code>. Use a non-breaking space: {{nobr|<code>12{{tl|nbsp}}&amp;deg;C</code>}}, not {{nobr|<s><code>12&amp;deg;C</code></s>}} nor {{nobr|<s><code>12&amp;deg;{{t|nbsp}}C</code></s> }} {{nobr|({{xt|12{{nbsp}}&deg;C}}, not {{!xt|12&deg;C}} nor {{!xt|12&deg;{{nbsp}}C}}). }}
|-
| degree Celsius {{nobr|({{em|not}} degree centigrade)}}
| {{xt|&deg;C}} ({{em|not}} {{!xt|C}})
|-
| [[kelvin]] {{nobr|({{em|not}} degree kelvin)}}
| {{xt|K}} ({{em|not}} {{!xt|&deg;K}})
|
|-
| rowspan = 2 {{Vert header|va=middle|<small>'''Energy'''</small>}}<!-- - - - WARNING! ADJUST ROWSPAN WHEN ADDING/REMOVING ROWS FROM A GROUP OF UNITS- - - -->
| {{plainlist|
* [[calorie]]
* small calorie
* gram calorie
}}
| {{xt|cal}}
| rowspan=2 | In certain subject areas, ''calorie'' is convention{{shy}}ally used alone. Articles following this practice should specify on first use whether the use refers to the small calorie or to the kilocalorie (large calorie). Providing conversions to [[International System of Units|SI]] units (usually calories to joules or kilocalories to kilojoules) may also be useful. A kilocalorie ({{xt|kcal}}) is 1000 calories. A calorie (small calorie) is the amount of energy required to heat 1 gram of water by 1 °C. A kilocalorie is therefore also a kilogram calorie.
|-
| {{plainlist|
* [[kilocalorie]]
* large calorie
* kilogram calorie
* ({{em|not}} Calorie{{snd}}{{nobr|can be ambiguous)}}
}}
| {{xt|kcal}}
|}

====Quantities of bytes and bits <span id="Binary prefixes"></span>====
{{shortcut|WP:COMPUNITS}}
In quantities of [[bit (computing)|bit]]s and [[byte]]s, the prefixes {{xtn|kilo-}} (symbol {{xtn|k}} or {{xtn|K}}), {{xtn|mega-}} ({{xtn|M}}), {{xtn|giga-}} ({{xtn|G}}), {{xtn|tera-}} ({{xtn|T}}), etc., are ambiguous. They may be based on a decimal system (like the standard [[International System of Units|SI]] prefixes), meaning 10<sup>3</sup>, 10<sup>6</sup>, 10<sup>9</sup>, 10<sup>12</sup>, etc., or they may be based on a binary system, meaning 2<sup>10</sup>, 2<sup>20</sup>, 2<sup>30</sup>, 2<sup>40</sup>, etc. The binary meanings are more commonly used in relation to solid-state memory (such as [[Random-access memory|RAM]]), while the decimal meanings are more common for data transmission rates, disk storage and in theoretical calculations in modern academic textbooks.
{{Bit and byte prefixes}}
Follow these recommendations when using these prefixes in Wikipedia articles:

* Following the SI standard, a lower-case {{xt|k}} should be used for "kilo-" whenever it means 1000 in computing contexts, whereas a capital {{xt|K}} should be used instead to indicate the binary prefix for 1024 according to JEDEC. (If, under the exceptions detailed further below, the article otherwise uses IEC prefixes for binary units, use {{xt|Ki}} instead).
* Do not assume that the binary or decimal meaning of prefixes will be obvious to everyone. Explicitly specify the meaning of k and K as well as the primary meaning of M, G, T, etc. in an article ({{tlx|BDprefix}} is a convenient helper). Consistency within each article is desirable, but the need for consistency may be balanced with other considerations.
* The definition most relevant to the article should be chosen as primary for that article, e.g. specify a binary definition in an article on RAM, decimal definition in an article on [[hard drives]], [[bit rate]]s, and a binary definition for Windows file sizes, despite files usually being stored on hard drives.
* Where consistency is not possible, specify wherever there is a deviation from the primary definition.
* Disambiguation should be shown in bytes or bits, with clear indication of whether in binary or decimal base. There is no preference in the way to indicate the number of bytes and bits, but the notation style should be consistent within an article. Acceptable examples include:
** {{xt|A 64{{nbsp}}MB ({{nowrap|64{{nbsp}}×{{nbsp}}1024<sup>2</sup>-byte)}} video card and a 100{{nbsp}}GB {{nowrap|(100{{nbsp}}×{{nbsp}}1000<sup>3</sup>-byte)}} hard drive}}
** {{xt|A 64{{nbsp}}MB ({{nowrap|64{{nbsp}}×{{nbsp}}2<sup>20</sup>-byte)}} video card and a 100{{nbsp}}GB {{nowrap|(100{{nbsp}}×{{nbsp}}10<sup>9</sup>-byte)}} hard drive}}
** {{xt|A 64{{nbsp}}MB {{nowrap|(67,108,864-byte)}} video card and a 100{{nbsp}}GB {{nowrap|(100,000,000,000-byte)}} hard drive}}
* Avoid inconsistent combinations such as {{!xt|A 64{{nbsp}}MB {{nowrap|(67,108,864-byte)}} video card and a 100{{nbsp}}GB {{nowrap|(100{{nbsp}}×{{nbsp}}1000<sup>3</sup>-byte)}} hard drive}}. Footnotes, such as those seen in [//en.wikipedia.org/w/index.php?title=Power_Macintosh_5500&oldid=218088888 {{nowrap|Power Macintosh 5500}}], may be used for disambiguation.
* Unless explicitly stated otherwise, one byte is eight bits {{crossref|(see {{section link|Byte|History}})}}.

The [[IEC prefix]]es {{xtn|kibi-}} (symbol {{xtn|Ki}}), {{xtn|mebi-}} ({{xtn|Mi}}), {{xtn|gibi-}} ({{xtn|Gi}}), etc., are generally not to be used except:{{efn|1=Wikipedia follows common practice regarding [[byte]]s and other data traditionally quantified using [[binary prefix]]es (e.g. {{xtn|mega-}} and {{xtn|kilo-}}, meaning 2<sup>20</sup> and 2<sup>10</sup> respectively) and their unit symbols (e.g. {{xtn|MB}} and {{xtn|KB}}) for RAM and [[decimal prefix]]es for most other uses. Despite the IEC's 1998 international standard creating several new binary prefixes (e.g. mebi-, kibi-, etc.) to distinguish the meaning of the decimal [[SI prefix]]es (e.g. {{xtn|mega-}} and {{xtn|kilo-}}, meaning 10<sup>6</sup> and 10<sup>3</sup> respectively) from the binary ones, and the subsequent incorporation of these IEC prefixes into the [[IEC 80000-13|ISO/IEC 80000]], consensus on Wikipedia in computing-related contexts favours the retention of the more familiar but ambiguous units {{xtn|KB}}, {{xtn|MB}}, {{xtn|GB}}, {{xtn|TB}}, {{xtn|PB}}, {{xtn|EB}}, etc. over use of unambiguous IEC binary prefixes. {{crossref|For detailed discussion, see [[WT:Manual of Style (dates and numbers)/Archive/Complete rewrite of Units of Measurements (June 2008)]].}} }}
* when the majority of cited sources on the article topic use IEC prefixes;
* in a direct quote using the IEC prefixes;
* when explicitly discussing the IEC prefixes; or
* in articles in which both types of prefix are used with neither clearly primary, or in which converting all quantities to one or the other type would be misleading or lose necessary precision, or declaring the actual meaning of a unit on each use would be impractical.

==Currencies and monetary values<span id="Currencies"></span>==
{{shortcut|WP:$|WP:&pound;|WP:€|MOS:CURRENCY}}
{{redirect|WP:CURRENCY|the WikiProject focusing on articles about currencies|Wikipedia:WikiProject Numismatics}}
{{see also|Wikipedia:WikiProject Numismatics/Style#Article titles}}

'''Choice of currency'''<!--Headings in this section formatted this way as permitted by MOS:PSEUDOHEAD: "If you want to reduce the size of the table of contents (TOC), use {{TOC limit}}... In cases where {{TOC limit}} cannot be used because of lower-level headings elsewhere in the article, then using bold for the sub-sub-sub headings causes the least annoyance for screen reader users [though to do so is] a rarity." -->

* In '''country-specific articles''', such as [[Economy of Australia]], use the currency of the subject country.
* In '''non-country-specific articles''' such as [[Wealth]], use US dollars ({{xt|US$123}} on first use, generally {{xt|$123}} thereafter), euros ({{xt|&euro;123}}), or pounds sterling ({{xt|&pound;123}}).

'''Currency names'''

* Do not capitalize the names or denominations of currencies, currency subdivisions, coins and banknotes: not {{!xt|a Five-Dollar bill, four Quarters, and one Penny total six Dollars one Cent}} but {{xt|a five-dollar bill, four quarters, and one penny total six dollars one cent}}. ''Exception:'' where otherwise required, as at the start of a sentence or in such forms as {{xt|Australian dollar}}.
* To pluralize {{xtn|euro}} use the standard English plurals ({{xt|ten euros and fifty cents}}), not the [[Linguistic issues concerning the euro#English|invariant plurals used for European Union legislation and banknotes]] ({{!xt|ten euro and fifty cent}}). For the adjectival form, use a hyphenated singular ({{xt|a two-euro pen and a ten-cent coin}}). 
* Link the first occurrence of lesser-known currencies ({{xt|[[Mongolian tögrög]]s}}).<!-- Should a symbol be introduced at this time? -->

'''Currency symbols'''<!-- Symbols, signifiers, abbreviations? See [[ISO 4217]] and [[currency symbol]]s. -->

* In general, the first mention of a particular currency should use its full, unambiguous signifier (e.g. {{xt|A$52}}), with subsequent references using just the appropriate symbol (e.g. {{xt|$88}}), unless this would be unclear. {{em|Exceptions:}}
** In an article referring to multiple currencies represented by the same symbol (e.g. the dollars of the US, Canada, Australia, New Zealand, and other countries{{snd}}{{crossref|see {{section link|Currency symbols|dollar variants}}}}) use the full signifier (e.g. {{xt|US$}}, {{xt|A$}}) each time, except (possibly) where a particular context makes this both unnecessary and undesirable.
** In articles entirely on EU-, UK- and/or US-related topics, all occurrences may be shortened ({{xt|&euro;26}}, {{xt|&pound;22}} or {{xt|$34}}), unless this would be unclear.
* The [[pound sterling]] is represented by the {{xt|&pound;}} symbol, with one horizontal bar. The double-barred {{!xt|&#8356;}} symbol is ambiguous, as it has also been used for the [[Italian lira]] and other currencies. For non-British currencies that use pounds or a pound symbol (e.g. the [[Irish pound]], IR&pound;) use the symbol conventionally preferred for that currency.<!-- If no modern currency still uses the ₤ symbol, the developers should be asked to remove it from the edit tool box to prevent its misuse. -->
* If there is no common English abbreviation or symbol, follow the [[ISO 4217]] standard. {{crossref|See also [[List of circulating currencies]].}}

{{Anchor|Formatting of monetary values}}'''Formatting'''

{{Anchor|Format}}<!--Old, imprecise heading, may be linked to.-->
* A period (full stop, <code>.</code>) is used as the decimal point{{snd}}never a comma ({{xt|$6.57}}, not {{!xt|$6,57}}).
* {{crossref|For the grouping of digits (e.g. {{xt|&pound;1,234,567}}) see {{section link||Grouping of digits}}, above.}}
* Do not place a currency symbol {{em|after}} the accompanying numeric figures (e.g. {{!xt|123$}}, {{!xt|123&pound;}}, {{!xt|123&euro;}}) unless that is the normal convention for that symbol when writing in English: {{xt|smaller British coins include 1p, 2p, and 5p denominations}}. Never use forms such as {{!xt|$US123}} or {{!xt|$123 (US)}}.
* Currency abbreviations that come before the numeric value are {{em|unspaced}} if they consist of a nonalphabetic symbol only, or end in a symbol ({{xt|&pound;123}};{{nbsp}}{{nbsp}} {{xt|&euro;123}}); but {{em|spaced}} if alphabetic ({{xt|R{{nbsp}}75}}).
* Ranges should be expressed giving the currency signifier just once: {{xt|$250{{ndash}}300}}, not {{!xt|$250{{ndash}}$300}}.
* {{xt|million}} and {{xt|billion}} should be spelled out on first use, and (optionally) abbreviated {{xt|M}} or {{xt|bn}} (both unspaced) thereafter: {{xt|She received &pound;70 million and her son &pound;10M}}; {{xt|the school's share was $250{{ndash}}300 million, and the charity's $400{{ndash}}450M}}.
* In general, a currency symbol should be accompanied by a numeric amount e.g. not {{!xt|He converted his US$ to A$}} but {{xt|He converted his US dollars to Australian dollars}} or {{xt|He exchanged the US$100 note for Australian dollars}}.
** Exceptions may occur in tables and infoboxes where space is limited e.g. {{xt|Currencies accepted: [[United States dollar|US$]], [[Swiss franc|SFr]], [[British pound|GB&pound;]], [[Euro|&euro;]]}}. It may be appropriate to wikilink such uses, or add an explanatory note.

'''Conversions'''

* Conversions of {{em|less-familiar currencies}} may be provided in terms of more familiar currencies{{snd}}such as the US dollar, euro or pound sterling{{snd}}using an appropriate rate (which is often {{em|not}} the current exchange rate). Conversions should be in parentheses after the original currency, rounding to avoid [[false precision]] (two significant digits is usually sufficient, as most exchange rates fluctuate significantly), with at least the year given as a rough point of conversion rate reference; e.g. {{xt|Since 2001 the grant has been 10,000,000 [[Swedish krona|Swedish kronor]] ($1.4M, &euro;970,000, or &pound;850,000 {{as of|2009|08|lc=on}})}}, not {{!xt|($1,390,570, &euro;971,673 or &pound;848,646)}}
* For {{em|obsolete currencies}}, provide an equivalent (formatted as a conversion) if possible, in the modern replacement currency (e.g. decimal pounds for historical pre-decimal pounds-and-shillings), or a US-dollar equivalent where there is no modern equivalent.
* In some cases, it may be appropriate to provide a conversion accounting for inflation or deflation over time. {{crossref|See {{tlx|Inflation}} and {{tlx|Inflation-fn}}.}}

==Common mathematical symbols<span id="Minus sign"></span>==
{{shortcut|WP:COMMONMATH||MOS:MINUS}}
{{See also|Wikipedia:Manual of Style/Mathematics|Help:Displaying a formula}}
* The ''Insert'' menu below the editing window gives a more complete list of math symbols, and allows symbols to be inserted without the HTML encoding (e.g. <code>&amp;divide;</code>) shown here.
* Spaces are placed to left and right when a symbol is used {{nobr|[[binary operation|with two operands]]}} ({{xt|the sum 4 + 5}}), but no space is used when {{nobr|[[unary operation |there is one operand]]}} ({{xt|the value&nbsp;+5}}). ''Exception:'' spaces are usually omitted in inline fractions formed with <code>/</code>: {{xt|3/4}} not {{!xt|{{nobr|3 / 4}}}}.
* The {{tlx|mvar}} (for single-letter variables) and {{tlx|math}} (for more complicated expressions) templates are available to display mathematical formulas in a manner distinct from surrounding text.
* The {{tlx|nbsp}} and {{tlx|nowrap}} templates may be used to prevent awkward linebreaks.

{{clear right}}
{|class="wikitable" style="align: center; text-align: center;"
|+Common mathematical symbols
|-
! width=110|Symbol name
! width= 80|Example
! width=335|Markup
! Comments
|-
| rowspan=2| [[Plus sign|Plus /<br />positive]]
| {{math|''x'' + ''y''}}
| <source lang="text" inline>{{math|''x'' + ''y''}}</source>
| rowspan=2|
|-
| {{math|+''y''}}
| <source lang="text" inline>{{math|+''y''}}</source>
|-
| rowspan=2|[[Minus sign|Minus /<br />negative]]
| {{math|''x'' &minus; ''y''}}
| <source lang="text" inline>{{math|''x'' &minus; ''y''}}</source>
| rowspan=2|Do not use hyphens ({{!xt|<source lang="text" inline>-</source>}}) or dashes ({{!xt|{{tlx|ndash}}}} {{nobr|or {{!xt|{{tlx|mdash}}}}).}}
|-
| {{math|&minus;''y''}}
| <source lang="text" inline>{{math|&minus;''y''}}</source>
|-
|  rowspan=2| [[Plus-minus sign|Plus-minus /<br />minus-plus]]
| 41.5 &plusmn; 0.3
| <source lang="text" inline>41.5 &plusmn; 0.3</source>
| rowspan=3|
|-
| {{math|1={{nobr|1= &minus;(&plusmn;''a'') = &#8723;''a''}}}}
| {{nobr|1=<source lang="text" inline>{{math|1=&minus;(&plusmn;''a'') = &#8723;''a''}}</source> }}
|-
| Multiplication,<br />dot
| {{math|''x'' &sdot; ''y''}}
| <source lang="text" inline>{{math|''x'' &sdot; ''y''}}</source> 
|-
| [[Multiplication sign|Multiplication]],<br />cross
| {{math|''x'' &times; ''y''}}
| <source lang="text" inline>{{math|''x'' &times; ''y''}}</source> 
| Do not use the letter {{!xt|x}} to indicate multiplication. However, an {{em|unspaced}} {{xt|x}} may be used as a substitute for "by" in common terms such as [[4x4|{{xt|4x4}}]]. 
|-
| [[Division sign|Division]], obelus
| {{math|''x'' &divide; ''y''}}
| <source lang="text" inline>{{math|''x'' &divide; ''y''}}</source>
|
|-
| [[Equal sign|Equal / equals]]
| {{math|1=''x'' = ''y''}}
| <source lang="text" inline>{{math|1=''x'' = ''y''}}</source> or<br /><source lang="text" inline>{{math|''x'' {{=}} ''y''}}</source>
| Note the use of <source lang="text" inline>1=</source> or <source lang="text" inline>{{=}}</source> to make the template parameters work correctly
|-
| [[Not equal sign|Not equal]]
| {{math|''x'' &ne; ''y''}}
| <source lang="text" inline>{{math|''x'' &ne; ''y''}}</source>
| rowspan=6|
|-
| [[Approximate sign|Approx. equal]]
| {{math|''&pi;'' &asymp; 3.14}}
| <source lang="text" inline>{{math|''&pi;'' &asymp; 3.14}}</source>
|-
| [[Less than sign|Less than]]
| {{math|''x'' &lt; ''y''}}
| <source lang="text" inline>{{math|''x'' &lt; ''y''}}</source>
|-
| [[Less than or equal to|Less or equal]]
| {{math|''x'' &le; ''y''}}
| <source lang="text" inline>{{math|''x'' &le; ''y''}}</source>
|-
| [[Greater than sign|Greater than]]
| {{math|''x'' &gt; ''y''}}
| <source lang="text" inline>{{math|''x'' &gt; ''y''}}</source>
|-
| [[Greater than or equal to|Greater or equal]]
| {{math|''x'' &ge; ''y''}}
| <source lang="text" inline>{{math|''x'' &ge; ''y''}}</source>
|}

==Geographical coordinates==
<div style="float:right; width:100px;">{{Shortcut|MOS:COORDS|WP:COORDINATES}}</div>

:{{crossref|For draft guidance on, and examples of, coordinates for linear features, see [[Wikipedia:WikiProject Geographical coordinates/Linear]].}}

:'''Quick guide''':

{{coord how-to}}
 
[[Geographical coordinates]] on Earth should be entered using a template to standardise the format and to provide a link to maps of the coordinates. As long as the templates are adhered to, a robot performs the functions automatically. 

First, [[Wikipedia:Obtaining geographic coordinates|obtain the coordinates]]. Avoid [[Wikipedia:WikiProject Geographical coordinates#Precision|excessive precision]].

The {{tlx|Coord}} template offers users a choice of display format through [[Help:User style|user style]]s, emits a [[Geo microformat]], and is recognised (in the {{em|title}} position) by the "nearby" feature of Wikipedia's mobile apps and by external service providers such as Google Maps and Google Earth, and Yahoo. Infoboxes automatically emit {{tlx|Coord}}.

The following formats are available. 
* For degrees only (including decimal values): {{tlc|coord|2={{var|dd}}|3={{var|N/S}}|4={{var|dd}}|5={{var|E/W}}}}
* For degrees/minutes: {{tlc|coord|2={{var|dd}}|3={{var|mm}}|4={{var|N/S}}|5={{var|dd}}|6={{var|mm}}|7={{var|E/W}}}}
* For degrees/minutes/seconds: {{tlc|coord|2={{var|dd}}|3={{var|mm}}|4={{var|ss}}|5={{var|N/S}}|6={{var|dd}}|7={{var|mm}}|8={{var|ss}}|9={{var|E/W}}}}

where:
* {{var|dd}}, {{var|mm}}, {{var|ss}} are the degrees, minutes and seconds, respectively;
* {{var|N/S}} is either <kbd>N</kbd> for northern or <kbd>S</kbd> for southern [[latitude]]s;
* {{var|E/W}} is either <kbd>E</kbd> for eastern or <kbd>W</kbd> for western [[longitude]]s;
* negative values may be used in lieu of <kbd>S</kbd> and <kbd>W</kbd> to denote Southern and Western [[Hemisphere of the Earth|Hemispheres]]

For example:

For the city of [[Oslo]], located at 59° 55&prime; N, 10° 44&prime; E:
: <code><nowiki>{{coord|59|55|N|10|44|E}}</nowiki></code>{{snd}}which becomes {{coord|59|55|N|10|44|E}}

For a country, like [[Botswana]], less precision is appropriate:
: <code><nowiki>{{coord|22|S|24|E}}</nowiki></code>{{snd}}which becomes {{coord|22|S|24|E}}

Higher levels of precision are obtained by using seconds:
: <code><nowiki>{{coord|33|56|24|N|118|24|00|W}}</nowiki></code>{{snd}}which becomes {{coord|33|56|24|N|118|24|00|W}}

Coordinates can be entered as decimal values
: <code><nowiki>{{coord|33.94|S|118.40|W}}</nowiki></code>{{snd}}which becomes {{coord|33.94|S|118.40|W}}

Increasing or decreasing the number of decimal places controls the precision. Trailing zeros should be used as needed to ensure that both values have the same level of precision. 

[[London Heathrow Airport]], [[Amsterdam]], [[Jan Mayen]] and [[Mount Baker]] are examples of articles that contain geographical coordinates.

Generally, the larger the object being mapped, the {{em|less precise}} the coordinates should be. For example, if just giving the location of a city, precision greater than 100{{nbsp}}meters is not needed unless specifying a particular point in the city, for example the central administrative building. Specific buildings or other objects of similar size would justify precisions down to 10{{nbsp}}meters or even one meter in some cases (1′′ ~15{{nbsp}}m to 30{{nbsp}}m, 0.0001° ~5.6{{nbsp}}m to 10{{nbsp}}m).

The final field, following the E/W, is available for attributes such as <code>type:</code>, <code>region:</code>, or <code>scale:</code> {{crossref|(the codes are documented at [[Template:Coord/doc#Coordinate parameters]])}}.

When adding coordinates, please remove the {{tlx|coord missing}} tag from the article, if present. 

{{Crossref|For more information, see [[Wikipedia:WikiProject Geographical coordinates|the geographical coordinates WikiProject]].}}

Templates other than {{tlx|coord}} should use the following variable names for coordinates: {{var|lat_d}}, {{var|lat_m}}, {{var|lat_s}}, {{var|lat_NS}}, {{var|long_d}}, {{var|long_m}}, {{var|long_s}}, {{var|long_EW}}.

==See also==
* [[Wikipedia:Naming conventions (numbers and dates)]]
* [[Wikipedia:Date formattings]]
* [[m:Help:Date formatting feature]] at Meta
* {{section link|m:Help:Calculation|Displaying numbers and numeric expressions}} at Meta

==Notes==
{{Notelist|35em}}

==References==
{{Reflist|35em}}

{{Style wide}}
{{Math templates}}

[[Category:Wikipedia Manual of Style (formatting)]]
[[Category:Wikipedia naming conventions|Dates and numbers]]