# AM, PM, Noon & Midnight **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [July 20, 1999, 7:31pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102 "1999-07-20T19:31:00Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Kimballkid](https://avatars.discourse-cdn.com/v4/letter/k/b5a626/32.png) [@Kimballkid](https://boards.straightdope.com/u/Kimballkid)\ **Post date:** [June 18, 2014, 6:32pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/21 "2014-06-18T18:32:20Z")
Don’t argue with an idiot, it will just frustrate you and amuse the idiot. ---
**Author:** ![DataX](https://avatars.discourse-cdn.com/v4/letter/d/e99b99/32.png) [@DataX](https://boards.straightdope.com/u/DataX)\ **Post date:** [June 18, 2014, 6:32pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/22 "2014-06-18T18:32:58Z")
> [@pulykamell](#): > > Think about that for a second. The time after 12 noon is 12:01 a.m.? The “afternoon” is “a.m.”? I think not. That link makes an argument, but it is not the one that is used by any human being I know. Nobody calls 12:30 after noon “12:30 a.m.” Nobody. I see how you can make an argument for it, but it’s all moot, as that’s not how it is actually used in real life, which is all that matters. > > Anyhow, I avoid the ambiguity by writing 12 noon and 12 midnight but, conventionally, it’s always been 12 a.m. = midnight, 12 p.m. = noon. Agreed - while it is nice to be non ambiguous about stuff - computers and modern record keeping - have sort of made this point moot - to me there is only one obvious choice. It is pretty common now a days to keep at least some records by minute. It looks silly to have these lists of numbers have one single minute with a different suffix every 720 minutes. Nor - in the case I am describing is it ambiguous - since you can see where it is - no one would be confused about: 11:57 AM 11:58 AM 11:59 AM 12:00 PM 12:01 PM 12:02 PM 12:03 PM vs 11:57 AM 11:58 AM 11:59 AM 12:00 AM 12:01 PM 12:02 PM 12:03 PM The second version looks stupid though - It gives the ridiculous result of having the hour switch over with the suffix one minute later. It looks weird - and makes no sense to do it that way. If neither is right - pick the option that is simpler. I can think of no rational reason for 12 noon to be AM - and at least a couple reasons (for programmers and designers of mechanical digital clocks) for it to be the other way. I’m curious if any time standard uses AM for 12 NOON. I haven’t checked real hard, but in the situations I am familiar with - if there is an option for AM/PM vs 24 hour - it is noon is PM. In other words: Noon is 12 PM since one minute after noon is 12:01 PM but I will continue to use noon in situations where it would be ambiguous. Luckily that is pretty rare. ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [June 18, 2014, 6:37pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/23 "2014-06-18T18:37:27Z")
> [@DataX](#): > > A > I can think of no rational reason for 12 noon to be AM - and at least a couple reasons (for programmers and designers of mechanical digital clocks) for it to be the other way. I only skimmed the linked thread, but I think the argument was to continue a.m. through 12, and once you flip back to 1 o’clock, go to p.m. There is a certain logic to that. So, it’d go 11:59 a.m., 12:00 a.m., 12:01 a.m., … 12:59 a.m., 1:00 p.m. I guess it could have gone that way, but it didn’t. ---
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [June 18, 2014, 6:56pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/24 "2014-06-18T18:56:56Z")
Yes, noon and midnight are their own entities, being instants outside of the AM and PM periods. Of course, even with the 24-hour clock, there’s the issue of “which day does midnight belong to?” The way I understand it, 00:00 is the midnight starting a day, and 24:00 is the midnight ending a day. So 24:00 on Thursday is the same instant as 00:00 on Friday; I have seen train schedules that say things like ‘arrival 24:35’ to refer ro a service which started before midnight. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [June 18, 2014, 7:05pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/25 "2014-06-18T19:05:09Z")
I don’t like “12 PM.” Why not just an unambiguous “12:01 PM” or “11:59 AM”? Better to get there a minute late than 12 hours too early. :rolleyes: ---
**Author:** ![BubbaDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bubbadog/32/333_2.png) [@BubbaDog](https://boards.straightdope.com/u/BubbaDog)\ **Post date:** [June 18, 2014, 7:08pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/26 "2014-06-18T19:08:56Z")
> [@running\_coach](#): > > He’s also neglecting to mention he wrote the article he linked to. …and he wouldn’t be the first person on this board who authored something somewhere else on the internet and then tried to use it as a cite. In any case there appears to be a number of people in California that are misinformed victims of a radio host. ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [June 18, 2014, 7:17pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/27 "2014-06-18T19:17:36Z")
> [@BubbaDog](#): > > …and he wouldn’t be the first person on this board who authored something somewhere else on the internet and then tried to use it as a cite. > > In any case there appears to be a number of people in California that are misinformed victims of a radio host. I’m surprised he has any listeners what with the confusion of when his show is on. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [June 18, 2014, 7:19pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/28 "2014-06-18T19:19:05Z")
> [@](#): > > Quoth **whomever the heck made post #13** : > > I remember working for the PBS Tv station and having three different style clocks we had to use. The garden variety AM/PM model, a 24-hour military time model, and some God awful 26 hour clock that was supposed to help us co-ordinate satillite hook-ups or some such time against different time zones. Don’t even ask me how that thing was supposed to work or be read because I had no idea (then again, only the engineers really had to worry about it and I was just a Master Control Operator). I suspect that that third clock was actually sidereal time. It’s not actually a 26-hour clock, it’s a 24 hour one, just with slightly shorter hours (but then, the poster admitted that e wasn’t sure how it worked). Just as a normal clock tracks (roughly, on average) when the Sun rises and sets, a sidereal clock tracks when the stars rise and set. One can see how this might have some relevance for satellite tracking, since satellite orbits would probably be specified in a star-based coordinate system. ---
**Author:** ![fiddlesticks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fiddlesticks/32/18129_2.png) [@fiddlesticks](https://boards.straightdope.com/u/fiddlesticks)\ **Post date:** [June 18, 2014, 10:22pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/29 "2014-06-18T22:22:20Z")
The Y2K bug erased all the SDMB pre-2000 poster names! See, the doomsayers were right after all! We didn’t listen! ---
**Author:** ![DrDeth](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@DrDeth](https://boards.straightdope.com/u/DrDeth)\ **Post date:** [June 18, 2014, 10:29pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/30 "2014-06-18T22:29:31Z")
Noon is 12NN, Midnite is 12MN. But yes, since one split second after 12MN is 12.00001 AM, you can say 12AM without being a idiot. ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [June 18, 2014, 10:34pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/31 "2014-06-18T22:34:33Z")
zombie or no switching AM and PM doesn’t solve the problem, though it’s a novel suggestion. ---
**Author:** ![Omar\_Little](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omar_little/32/269_2.png) [@Omar\_Little](https://boards.straightdope.com/u/Omar_Little)\ **Post date:** [June 20, 2014, 6:24pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/32 "2014-06-20T18:24:33Z")
The correct solution is that there be no 12:01, 12:02, etc. It should be 0:01, 0:02, etc with the AM and PM shown as follows: 11:58 pm 11:59 pm 12:00 pm 0:01 am 0:02 am Because that is what is really intended by current convention of calling midnight 12:00 am. ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [June 20, 2014, 6:32pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/33 "2014-06-20T18:32:21Z")
> [@Omar\_Little](#): > > The correct solution is that there be no 12:01, 12:02, etc. It should be 0:01, 0:02, etc with the AM and PM shown as follows: > > 11:58 pm > 11:59 pm > 12:00 pm > 0:01 am > 0:02 am > > Because that is what is really intended by current convention of calling midnight 12:00 am. Or you could go 0:00 a.m. ---
**Author:** ![Inner\_Stickler](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/inner_stickler/32/318_2.png) [@Inner\_Stickler](https://boards.straightdope.com/u/Inner_Stickler)\ **Post date:** [June 20, 2014, 6:37pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/34 "2014-06-20T18:37:28Z")
Look, all I need is an obvious and unambiguous way to remember if I fuck up my alarm clock and have to reset the time between midnight and one in the morning, do I want it to say PM or AM? You laugh but this has been an issue in the past. ---
**Author:** ![Omar\_Little](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omar_little/32/269_2.png) [@Omar\_Little](https://boards.straightdope.com/u/Omar_Little)\ **Post date:** [June 20, 2014, 6:39pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/35 "2014-06-20T18:39:18Z")
> [@pulykamell](#): > > Or you could go 0:00 a.m. That would require replacing the 12 on all clocks. As it stands, you could just declare that the highest time is 12:00 and then resets to 0:00:01 ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [June 20, 2014, 7:06pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/36 "2014-06-20T19:06:31Z")
> [@Bob\_Bishop](#): > > You are all wrong! The correct answer is: Midnight is 12PM (followed by 12:01PM,12:02PM …), and Noon is 12AM (followed by 12:01AM, 12:02AM …). For the correct explanations, read this: [HOAX.COM: unravelling the truth from fiction, past to present...](http://www.simplecodeworks.com/IQ/midnight.html) You’re not only dead wrong, you’re really adamant about it, which is amusing. Try using your logic again, except, instead of counting hours, count minutes or seconds. You’ll see where your logic fails. One second after noon is one second post-meridium. Even if we think of seconds as being fractions of hours (which is correct), one fraction of an hour after noon is one fraction of an hour AFTER noon, not before it. In addition to being wrong, you’re contradicting the way every computer I know of works (including Macs, Linux, UNIX, Windows, Android, TOPS10, TOPS20, OS8, RT11, and no doubt others.) So, you’re convincing everyone to use a new “standard”, which even if it was correct from some point of view, would lead to far more confusion than being “wrong” but consistent. Finally, the guy I know of who knows the most about time is Dave Mills, originally of UCS (ucs.edu), who invented the Network Time Protocol. He’s deeply educated on the issues of measuring, recording, and communicating about time. Consider reading his papers; you’ll find them authoritative, informative, and interesting. I wish I’d kept all his old work; you can no longer find all of it on line. But he covers all the stuff from early time recording through the Georgian calendar revolution up to modern calculations of the leap-second, and diverse issues that need to be taken into account when trying to synchronize an arbitrary-topology plesiochronous network. > [@Omar\_Little](#): > > The correct solution is that there be no 12:01, 12:02, etc. It should be 0:01, 0:02, etc with the AM and PM shown as follows: > > 11:58 pm > 11:59 pm > 12:00 pm > 0:01 am > 0:02 am > > Because that is what is really intended by current convention of calling midnight 12:00 am. I wouldn’t use 0: unless I were using a 24-hour clock, so it’d be 23:59, 0:00. (Or as mentioned, 2400 using military time, but it’s been long since I did that.) > [@Inner\_Stickler](#): > > Look, all I need is an obvious and unambiguous way to remember if I fuck up my alarm clock and have to reset the time between midnight and one in the morning, do I want it to say PM or AM? > > You laugh but this has been an issue in the past. Since it’s after midnight, it’s ante-meridium, so AM. 12:01 AM is a minute after midnight. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [June 20, 2014, 7:14pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/37 "2014-06-20T19:14:44Z")
I’m going to retract my statement that he’s dead wrong. On rereading, his argument does make sense, even if it is wrong from a different point of view. However, it’s wrong because it disagrees with nearly universal conventions: it would cause even more confusion when trying to communicate. ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [June 20, 2014, 7:17pm UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/38 "2014-06-20T19:17:18Z")
> [@Omar\_Little](#): > > That would require replacing the 12 on all clocks. As it stands, you could just declare that the highest time is 12:00 and then resets to 0:00:01 Going from 12:00 to 0:01 requires no more changes than going from 11:59 to 0:00. Furthermore, it’s more consistent. Try adding seconds to your proposal\* and see how it works out! If we’re going to use 0, it should start at midnight! - Which I see you just did, but not consistently with your earlier example. Which is it? ---
**Author:** ![qazwart](https://avatars.discourse-cdn.com/v4/letter/q/5fc32e/32.png) [@qazwart](https://boards.straightdope.com/u/qazwart)\ **Post date:** [June 22, 2014, 3:03am UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/39 "2014-06-22T03:03:42Z")
> [@septimus](#): > > I don’t like “12 PM.” Why not just an unambiguous “12:01 PM” or “11:59 AM”? > Better to get there a minute late than 12 hours too early. :rolleyes: I remembered a sign in the NY Subway talking about some hearing on the subway system and wanting input from the straphangers. The meeting according to the sign would start at 12PM. A week later, the sign changed the time of the meeting to 12:01pm. ---
**Author:** ![qazwart](https://avatars.discourse-cdn.com/v4/letter/q/5fc32e/32.png) [@qazwart](https://boards.straightdope.com/u/qazwart)\ **Post date:** [June 22, 2014, 3:13am UTC](https://boards.straightdope.com/t/am-pm-noon-midnight/2102/40 "2014-06-22T03:13:07Z")
I’ve noticed that much of the non-English speaking world uses a 24 hour clock. That is 5:00pm is 17:00. Is AM and PM a strictly Anglo phenomenon? If so, why the split? Did the rest of Europe abandon the AM/PM notation or did the British think drinking tea at 14:00 seem a bit late? [Previous page](https://boards.straightdope.com/t/am-pm-noon-midnight/2102.md?page=1) [Next page](https://boards.straightdope.com/t/am-pm-noon-midnight/2102.md?page=3)