Editing 12-hour clock (section)

==Related conventions==

===Typography===
The terms "a.m." and "p.m." are abbreviations of the Latin {{Lang|la|ante meridiem}} (before midday) and {{Lang|la|post meridiem}} (after midday). Depending on the [[style guide]] referenced, the abbreviations "a.m." and "p.m." are variously written in [[small capital]]s ("{{smallcaps|am}}" and "{{smallcaps|pm}}"),<ref>{{cite web |last1=Trask |first1=Larry |title=Small Capitals |url=https://www.sussex.ac.uk/informatics/punctuation/misc/small |website=University of Sussex Informatics |publisher=The University of Sussex |access-date=30 October 2024}}</ref><ref name="Chicago MOS">{{cite web |title=9.39: Numerals versus words for time of day |url=https://www.chicagomanualofstyle.org/book/ed18/part2/ch09/psec039.html |website=The Chicago Manual of Style Online |publisher=The University of Chicago |access-date=30 October 2024}}</ref> [[Letter case|uppercase]] letters without a [[full stop|period]] ("AM" and "PM"), uppercase letters with periods, or lowercase letters ("am" and "pm"<ref name=ESG /> or "a.m." and "p.m."<ref name="Chicago MOS"/>). With the advent of computer generated and printed schedules, especially airlines, advertising, and television promotions, the "M" character is often omitted as providing no additional information as in "9:30A" or "10:00P".<ref>{{cite web |last=Watson |first=James Robert |title=A more efficient way to denote am or pm |url=https://www.jamesrobertwatson.com/ampm.html |website=Jim Watson professor of design |access-date=August 30, 2022}}</ref>

Some style guides suggest the use of a space between the number and the a.m. or p.m. abbreviation.{{citation needed|date=March 2011}} Style guides recommend not using a.m. and p.m. without a time preceding it.<ref>Hacker, Diana, A Writer's Reference, six edition, Bedford, St Martin's, Boston, 2007, section M4-c, p.308.</ref>

The hour/minute separator [[Date and time representation by country|varies between countries]]: some use a colon, others use a period (full stop),<ref name=ESG>{{cite book |title=Economist Style Guide |page=185 |edition=12th |isbn=9781781258316 |publisher=[[The Economist]] |date=2018}}</ref> and still others use the letter h.{{citation needed|date=October 2021}}<!-- Dubious. I have seen the h notation many times but only ever with 24-hour clock. --> (In some usages, particularly "[[military time]]", of the [[24-hour clock]], there is no separator between hours and minutes.<ref>{{cite book |author=<!--Staff writer(s); no by-line.--> |date=May 27, 2015 |title=The Tongue and Quill |publisher=US Air Force |url=https://static.e-publishing.af.mil/production/1/saf_cn/publication/afh33-337/afh33-337.pdf |page=356 |access-date=26 October 2021 |archive-date=26 November 2020 |archive-url=https://web.archive.org/web/20201126183321/https://static.e-publishing.af.mil/production/1/saf_cn/publication/afh33-337/afh33-337.pdf |url-status=dead }} Air Force Handbook 33-337.</ref> This style is not generally seen when the 12-hour clock is used.)

=== Encoding ===
[[Unicode]] specifies [[codepoint]]s for ''a.m.'' and ''p.m.'' as [[precomposed character]]s, which are intended to be used only with [[CJK characters|Chinese-Japanese-Korean]] (CJK) character sets, as they take up exactly the same space as one CJK character: 
* {{unichar|33C2}}
* {{unichar|33D8}}

===Informal speech and rounding off===
In speaking, it is common to round the time to the nearest five&nbsp;minutes and/or express the time as the past (or to) the closest hour; for example, "five past five" (5:05). Minutes ''past'' the hour means those minutes are added to the hour; "ten past five" means 5:10. Minutes ''to, 'til'' and ''of'' the hour mean those minutes are subtracted; "ten of five", "ten 'til five", and "ten to five" all mean 4:50.

Fifteen&nbsp;minutes is often called a ''quarter hour'', and thirty&nbsp;minutes is often known as a ''half hour''. For example, 5:15 can be phrased "(a) quarter past five" or "five-fifteen"; 5:30 can be "half past five", "five-thirty" or simply "half five". The time 8:45 may be spoken as "eight&nbsp;forty-five" or "(a) quarter to nine".<ref>{{cite dictionary|title=quarter|dictionary=American Heritage Dictionary|edition=3rd|location=Boston|publisher=Houghton Mifflin|date=1992}} s.v. usage note at end of "quarter" entry.</ref> In some languages, e.g. Polish, rounding off is mandatory when using (spoken) 12-hour clock, but disallowed when using 24 hour notation. I.e. 15:12 might be pronounced as "quarter past three" or "fifteen-twelve", but ''not'' "three-twelve" or "quarter past fifteen".<ref>{{cite web |title=Określanie godzin i minut |url=https://sjp.pwn.pl/poradnia/haslo/Okreslanie-godzin-i-minut;19024.html |website=Słownik języka polskiego PWN |access-date=18 March 2025 |language=Polish}}</ref>

In older English, it was common for the number 25 to be expressed as "five-and-twenty".<ref>{{cite book |last1=Dickens |first1=Charles |title=Little Dorrit |date=1855 |page=Chapter 27}}</ref> In this way the time 8:35 might have been phrased as "five-and-twenty to 9",<ref>{{cite web |last1=Trudgill |first1=Peter |title=Number five-and-twenty: A fading linguistic practice |url=https://www.theneweuropean.co.uk/brexit-news-peter-trudgill-recounts-the-old-way-of-counting-80170/ |website=The New European |date=17 May 2020 |access-date=13 October 2022}}</ref> although this styling fell out of fashion in the later part of the 1900s and is now rarely used.<ref>{{cite web |last1=Swan |first1=Michael |title=Ask About English |url=https://www.bbc.co.uk/worldservice/learningenglish/radio/specials/1535_questionanswer/page63.shtml |website=BBC World Service |publisher=BBC |access-date=13 January 2021}}</ref>

Instead of meaning 5:30, the "half five" expression is sometimes used to mean 4:30, or "halfway to five", especially for regions such as the [[Midwestern United States|American Midwest]] and other areas that have been particularly [[German America|influenced by German culture]].{{cn|date=November 2023}} This meaning follows the pattern choices of many Germanic and [[Slavic languages]], including [[Serbo-Croatian]], [[Dutch language|Dutch]], [[Danish language|Danish]], [[Russian language|Russian]], [[Norwegian language|Norwegian]], and [[Swedish language|Swedish]], as well as [[Hungarian language|Hungarian]], [[Finnish language|Finnish]], and the languages of the [[Baltic states|Baltic States]].

Moreover, in situations where the relevant hour is obvious or has been recently mentioned, a speaker might omit the hour and just say "quarter to (the hour)", "half past" or "ten 'til" to avoid an elaborate sentence in informal conversations. These forms are often commonly used in television and radio broadcasts that cover multiple time zones at one-hour intervals.<ref>{{Cite magazine|magazine=TVTimes|date=21–27 May 1983|url=http://forums.doyouremember.co.uk/threads/8061-TVTimes-magazine-21-27-May-1983-part1 |archive-url=https://web.archive.org/web/20121018072904/http://forums.doyouremember.co.uk/threads/8061-TVTimes-magazine-21-27-May-1983-part1|archive-date=18 October 2012|url-status=live |title=TVTimes magazine 21-27 May 1983 part1 |access-date=8 October 2019}}</ref>

In describing a vague time of day, a speaker might say the phrase "seven-thirty, eight" to mean sometime around 7:30 or 8:00. Such phrasing can be misinterpreted for a specific time of day (here 7:38), especially by a listener not expecting an estimation. The phrase "''about'' seven-thirty ''or'' eight" clarifies this.

Some more ambiguous phrasing might be avoided. Within five&nbsp;minutes of the hour, the phrase "five of seven" (6:55) can be heard "five-oh-seven" (5:07). "Five ''to'' seven" or even "six&nbsp;fifty-five" clarifies this.

===Formal speech and times to the minute===
{{redirect|O'clock|the o'clock watch|O bag}}
{{Unreferenced section|date=October 2020}}
Minutes may be expressed as an exact number of minutes past the hour specifying the time of day (e.g., 6:32&nbsp;p.m. is "six&nbsp;thirty-two"). Additionally, when expressing the time using the "past (after)" or "to (before)" formula, it is conventional to choose the number of minutes below 30 (e.g., 6:32&nbsp;p.m. is conventionally "twenty-eight&nbsp;minutes to seven" rather than "thirty-two&nbsp;minutes past six").

In spoken English, full hours are often represented by the numbered hour followed by [[wikt:o'clock|''o'clock'']] (10:00 as ''ten o'clock'', 2:00 as ''two o'clock''). This may be followed by the "a.m." or "p.m." designator, though some phrases such as ''in the morning, in the afternoon, in the evening,'' or ''at night'' more commonly follow analog-style terms such as ''o'clock, half past three,'' and ''quarter to four. O'clock'' itself may be omitted, telling a time as ''four a.m.'' or ''four p.m.'' Minutes ":01" to ":09" are usually pronounced as ''oh one'' to ''oh nine'' (''nought'' or ''zero'' can also be used instead of ''oh''). Minutes ":10" to ":59" are pronounced as their usual number-words. For instance, 6:02&nbsp;a.m. can be pronounced ''six&nbsp;oh&nbsp;two&nbsp;a.m.'' whereas 6:32&nbsp;a.m. could be told as ''six&nbsp;thirty-two&nbsp;a.m.''.