Talk:12-hour clock

Table in noon and midnight section has incorrect entries
The NIST line is wrong. 12:01 am is 12:01 am. How else can you distinguish 12:01 am from 12:00 am? If it were 12:01 am and someone asked you the time, you would say 12:01 am. But 12:01 am is midnight according to the table. So when someone says it's 12:01 am, is it 12:01 am or midnight? This is ridiculous.

You use 12:01 am and 11:59 pm only when down-to-the-minute accuracy is not needed. While NIST doesn't explicitly say this, it is strongly implied (use in contracts is mentioned) and the only sensible interpretation. The table should reflect this.

It's nice to see the U.S. gov't finally got it right! (^_^)

Also, how about an entry for computers? It's not just digital watches. In fact, it's not just computers. It's digital displays in general.

Betaneptune (talk) 19:40, 19 November 2019 (UTC)


 * Are there any objections to changing "digital watches" to "digital displays" or "clocks with digital displays" or "digital clocks"? The first one is really too specific. Betaneptune (talk) 20:54, 20 October 2020 (UTC)
 * I don't mind changing "digital watches" to "clocks with digital displays" but you should start a new section rather than sticking this in the middle of a stale thread. Jc3s5h (talk) 22:36, 20 October 2020 (UTC)


 * Yes, it could be clearer. The intention, of course, is that 11:59 p.m. lasts up to 11:59.99; there is no midnight (the contract time changes at the instant of midnight from 11:59 to 12:01 a.m.); and 12:01 starts at 12:00.01
 * How can we express this more clearly? This is for contexts where the date is more important than the time to the exact second.  Dbfirs  21:08, 19 November 2019 (UTC)
 * My only concern is that the table possibly gives the mistaken impression that 12:01 AM and 11:59 PM are midnight and noon, respectively. Perhaps I'm going too much by how the article was years ago, the last time I took an active part in it, when it was a disaster. My impression here is that 12:01 AM and 11:59 PM are being used as close enough to midnight and noon for most purposes, but still different, so as to make clear what day is meant. But the article and/or table isn't making that clear. So why not just state that? That is clearly the intent of the NIST bit. --Betaneptune (talk) 21:49, 19 November 2019 (UTC)
 * Noon isn't involved here. The explanation is in the adjoining text.   Db<i style="color: #4fc;">f</i><i style="color: #6f6;">i</i><i style="color: #4e4;">r</i><i style="color: #4a4">s</i>  21:59, 19 November 2019 (UTC)
 * Right. Sorry. Strike noon. Should be beginning of day instead. Thanks. (^_^)  Betaneptune (talk) 22:43, 19 November 2019 (UTC)

"Japanese legal convention [dubious]"
The linked source didn't mention it being legally required or enforced (in fact, most digital watches follow the 11AM–12PM convention), but as someone who spent their childhood in Japan, I can tell you where it is used: television. Anchors on networks like NHK would always announce the time as 0 PM at noon, which means they use 0-indexed 12-hour notation. The linked source also mentioned that the 0-indexed 12-hour notation is taught at schools. 202.144.171.174 (talk) 16:31, 21 June 2020 (UTC)


 * What is the actual problem with it? The word legal in Japanese legal convention doesn't mean it's required to be used in digital watches or wherever but just that it's the convention used in Japanese legalese. One can find it used in the text of the law and in documents like vehicle insurance (per source). Here's the same thing put another way: . As the source and comment above show, the convention used in TV, radio, etc that uses 0 PM for noon follows "how it's taught in school" and is actually a logical extension of the legal one that uses 0 AM (午前0時) for midnight but 12 AM (午前12時) for noon (although at least one regulation exists that used 午後零時, i.e. 0 PM; see 午前と午後). Both calling it Japanese legal convention and actual values shown in table in the current revision of the article seem accurate to me.
 * The editor who added the template in Special:Diff/688937507 said in the edit summary that dubious Japanese legal convention makes no mention of "AM/PM" and didn't discuss it any further. If the problem is that the linked source and Japanese in general don't use the abbreviations AM/PM then it's technically correct and it probably should use 午前0時, 午前12時, and 午後12時 in the table to be truthful to typographic conventions, but 午前 and 午後 are considered equivalent to English AM and PM so I'm not sure if that would be any improvement in the context of noon/midnight distinction.
 * I can't see any other fault in either the source or the way it was used here. Does anyone object just removing that template? –<i style="text-transform:lowercase">MwGamera</i> (talk) 06:22, 15 August 2021 (UTC)
 * I have removed the dubious tag and added another column specifying the common usage of 0 PM for noon, since another source has explained the situation well. The fact is that the legalese is confusing therefore everyday use has deviated.-Miklcct (talk) 23:51, 19 January 2022 (UTC)

12 AM is noon and always has been
12 AM has never been midnight, and it doesn't logically make sense for it to be so why are 12 AM and 12 PM swapped 2601:242:4100:F200:418B:F12F:5C3:F4C0 (talk) 00:38, 24 February 2021 (UTC)
 * Every Wikipedia editor is unreliable. All contentious statements made in Wikipedia must obey the verifiability policy. A reliable source, the 2008 edition of the US Government Printing Office Style Manual is cited in the article and says that 12 AM is midnight of the day that is beginning. The 2016 edition says the same thing on page 275 (which is page 289 of the PDF). Since there is a significant source that says 12 a.m. is midnight, your assertion "12 AM has never been midnight" is just wrong. Jc3s5h (talk) 00:50, 24 February 2021 (UTC)


 * You are wrong about 12.00am and 12.00pm. The thing is that 12.00am comes directly after 11.59am and is am all the way through until it becomes 1.00pm - 12.00am - 12 midday - until the afternoon - 1 in the afternoon. Likewise, 12.00pm is 12 o'clock midnight and the time only becomes am (morning) when it becomes 1 in the morning - 1.00am. People have always got this wrong and I am surprised that Wikipedia is also making the same mistake.
 * Many thanks, Dave Rattle — Preceding unsigned comment added by 102.65.62.161 (talk) 07:37, 28 May 2021 (UTC)
 * Please have a look at any digital clock at any time between noon and 1 pm. What does the am/pm marker say? Case closed. &minus;Woodstone (talk) 12:38, 31 May 2021 (UTC)
 * Dave Rattle, 1) Don't put your contact information into discussions here. 2) If it is indeed am until 1:00pm, what do we make of 12:01 after noon?  How about 12:00:01?  12:00:00.1?  12:00:00.00000....[insert any finite number of zeros you like]....0001?  All of those times come AFTER noon, right? Uporządnicki (talk) 16:20, 8 September 2021 (UTC)


 * The day starts at 12:00 am. Later we get 12:01 am, 12:59 am, 1:00 am, . . ., 11:59 am, 12:00 pm, 1:00 pm, . . ., 11:59 pm, 12:00 am. The most logical, the most-often used, and in fact, the de facto convention is that 12am is midnight at the beginning of the day and 12pm is noon. Every digital clock I've ever seen, including embedded systems, follows this de facto convention. If you need to set a clock or alarm to 12:00 on a 12-hour digital clock or embedded system, you better know and use the de facto convention, or you'll get it wrong! And it has never been the case that we switch from am to pm or vice versa at 1:00.


 * The de facto convention is the most sensible, the most logical, follows the usual rollover rules with AM switching to PM and vice versa at 12:00, convention for the 12-hour clock. It also follows the KISS credo. Anything else is more complicated. And insisting that 12am and 12pm are illegitimate symbols for midnight and noon shows a slavish adherence to the definitions of am and pm that were made approx. 400 years ago. All other words are allowed to evolve. But for some reason, some people (fuddy-duddies), insist on using the original outdated, archaic definitions. It's well past, uh, time, to move on! Why make it more complicated than it has to be? Betaneptune (talk) 10:12, 2 March 2024 (UTC)
 * If you want to make people do what you think is logical, get yourself appointed Secretary of Commerce or Secretary of Defence of the United States. Then you'll be in charge of one of the two agencies in the US responsible for time dissemination, and a few hundred million people might care what you think. Until then you're an anonymous Wikipedia editor, with the degree of recognition that goes with that position. Jc3s5h (talk) 16:40, 2 March 2024 (UTC)

Does "Informal speech and rounding off" belong here?
it is useful, but most of the examples are not specific to 12 hour clock per se, could apply to 24hr time as well, I thinkFeldercarb (talk) 15:55, 8 June 2021 (UTC)

To add reference of a day start/end as per hindu calendar
It is notable to add the references of how the Hindu calendar defines the start of a day and end of day.

Extract from the page (Section: Sandhyakala in https://en.m.wikipedia.org/wiki/Sandhyavandanam) As per Hindu traditional calendar, the day starts with sunrise (i.e. from midnight of previous night until sunrise is considered part of previous day).

Thaejas (talk) 00:32, 11 September 2022 (UTC)
 * This article is about the 12-hour clock. How would you add information about the traditional start of a day in the Hindu traditional calendar to this article? Also, Wikipedia is not a reliable source so you would have to find  reliable sources for whatever you want to add. Jc3s5h (talk) 17:27, 12 September 2022 (UTC)