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A couple years ago, I switched all my personal clocks 24-hour notation. I live in the US, and 24-hour time is used very, very rarely. So, I haven't been able to listen to anyone say times aloud.

Here's my question: What is the proper way to say a time aloud in 24-hour notation?

"Fifteen o'clock" sounds bad to me. I think I like "Fifteen hours" best, but it sounds a little formal.

"Fifteen twenty-two" sounds okay to me, but still strange.

Is there a 'best practice' here?

Nathan G.
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    There is no reason you cannot say "fifteen o'clock," except when it's not 15:00. – apaderno Jul 20 '11 at 15:47
  • @kiamlaluno Is that what's commonly done in English-speaking countries that use 24-hour notation? If so, I'm happy to use it. – Nathan G. Jul 20 '11 at 15:48
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    I am used to American notation. The 24-hour format is used from the military, even in USA. I think they say 15:00, but o'clock is not associated with numbers from one to twelve only. You can say "fifteen o'clock" and all people would understand what you mean by o'clock; they will calculate which time you mean, and maybe they will tell you "you are using the military time." (I know that from my experience with my fiancé, who is American.) – apaderno Jul 20 '11 at 15:55
  • Please clarify what you mean by say a time aloud in 24-hour notation. Do you mean say it in such a way that the hearer always knows you're using 24-hour notation? Taking a specific case, do you want to say nine fifty-five, for example, or five to ten? – FumbleFingers Jul 20 '11 at 17:26
  • @Fumble I was hoping to learn of a 'best practice' way to speak it and let the hearer know I'm using 24-hour notation. But, if that is never done, I'll settle for converting to 12-hour. However, it seems (from the answers below) that one can speak aloud in 24-hour notation. – Nathan G. Jul 20 '11 at 20:01
  • @Nathan, The real question is how do you say any time before 1:00am in 24-hour notation (e.g., 00:30)? Is it half-past zero? – whoabackoff Jul 20 '11 at 20:15
  • @whoabackoff: I'd say Oh thirty if it was in a context where all times were named in 24hr format (discussing a bus timetable at work, for example). Otherwise, just the normal half-past twelve (midnight if there was any chance of confusion with 12:30pm). My problem is with saying 12:30pm in that style - I can't hack half-past midday or half-past noon, so if there was any ambiguity I'd just have to add the pm bit which I don't normally like saying. – FumbleFingers Jul 20 '11 at 20:25
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    @Nathan G. So all you really want to know is can you say See you at fifteen o'clock rather than the potentially ambiguous See you at three o'clock? – FumbleFingers Jul 20 '11 at 20:34

7 Answers7

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In 24-hour notation you never say o'clock. Say the value of the hours part first, then the minutes.

If the hours or minutes are less than 10, say Oh (for zero) first.

Non-military people don't usually say the "Oh" before hours, especially if the minutes are non-zero.

If the minutes are zero, say (hours) hundred. People (esp military) often say hundred hours (esp if the hours are less than 10).

0700 - Oh seven hundred [hours]

0701 - Oh seven Oh one

1500 - Fifteen hundred.

1503 - Fifteen Oh Three

1510 - Fifteen ten

1559 - Fifteen fifty-nine

I think there's a big problem with 1000. Nobody much likes saying ten hundred, but I don't know how you get around that if you must speak in 24-hour notation. Most people just say Ten o'clock and forget it.

In practice many of us mix traditional and 24-hour because (like you, I suspect) we have digital displays and can't always be bothered to mentally convert, say, 1550 into ten to four before speaking. You have to decide how far you want to take your own usage (partly dependent on how good you are at mental arithmetic :). I recommend reverting to traditional for 1000 at the very least.

LATER - Since posting this I've realised American (not British) usage accepts fifteen o'clock, for example, for 'exact hour' times after midday. But if you follow that link it's obvious this usage has fallen off significantly since the war. And if you switch the "corpus" to British, you'll see we've never used it enough to even show on the graph.

FumbleFingers
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    I think this is somewhat debatable. I think thirteen o'clock, eighteen o'click, twenty o'clock, etc. sound OK in the context of referring to 24-hour times. – Jez Jul 20 '11 at 16:01
  • @Jez: Wow! Twenty o'clock sounds really weird to me! It mixes 'modern, military time' terminology with the traditional form. But if you think it sounds okay, who am I to argue that you shouldn't? – FumbleFingers Jul 20 '11 at 16:15
  • I have always had my digital watch set to 24-hr time, and I don't hesitate to say "twenty o'clock". – Daniel Jul 20 '11 at 18:22
  • @drm65: Maybe there's an element of US/UK difference. I'd understand the time being referenced, of course, but I'd be astonished here in UK if my dentist's receptionist (who phones in the morning to remind everyone with an appointment later that day) were to tell me I'm due in at fifteen o'clock. – FumbleFingers Jul 20 '11 at 20:05
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    Deliberately saying Oh for zero leads to idioms like "getting up at oh-dark-thirty" meaning very early in the morning, when it's still dark. – Kate Gregory Jul 21 '11 at 13:10
  • I haven't heard oh-dark-thirty before, but I have a nephew who seems to use zero'clock for any time earlier than he would normally get up! – FumbleFingers Jul 21 '11 at 15:05
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    Reminds me of the opening of George Orwel's 1984, "It was a bright cold day in April and the clocks were striking thirteen...". As an English native speaker I would never use o'clock with numbers greater than 12. I would say, e.g. "fourteen hundred" or with times not on the hour, "fifteen twenty". Didn't "hundred hours" refer to an experement with metric time (with the hour divided into a hundred units?). – Matt Nov 22 '11 at 09:20
  • @Matt: Some say Orwell's line evokes a "military" future, and/or ironically juxtaposes "unlucky 13" with "the hopes of spring". Me, I'm with David Randall where he explicitly cites this expression as an example of an intriguing 'intro' device. – FumbleFingers Nov 22 '11 at 14:07
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    I've never heard "fifteen o'clock". It sounds weird to me. (Non-military American here.) – Monica Cellio Nov 22 '11 at 16:18
  • @Monica Cellio: I too think it's weird, and at first I assumed it could only be non-native speakers reading off times from their digital watches. But kiamlaluno assures us his American fiance says it; who am I to argue? – FumbleFingers Nov 22 '11 at 16:58
  • @FumbleFingers, just providing a data point. I wonder if it's regional, generational, something else? – Monica Cellio Nov 22 '11 at 23:09
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    @Monica: Well most of the votes went to Mr. Disappointment's summary of American military usage, so I guess that's considered equivalent to OP's 24-hour notation by the world at large. I worked for many years (in the UK) on various rota/schedule systems where we obviously use 24-hour notation. I know we never said anything like Eighteen Twelve hours for 6:12pm - but if I'm too wimpy to argue with kiamlaluno's fiancee, I'm definitely too wimpy to argue with the American military! :) – FumbleFingers Nov 22 '11 at 23:26
  • @FumbleFingers: Can you point to some source to back up your last edit? It would help me greatly. – drakorg Jan 26 '12 at 02:09
  • @Eduardo: I've just used NGram to check (link edited into the answer). It's now obvious to me that the American usage isn't new at all - it's something that was far more common a century ago (and particularly in the more "militarised" years from WW1-WW2). It had practically disappeared by the 1980s/90s, but I'm guessing digital clocks/watches are helping bring about a revival. Not for Brits though - it sounds really "ignorant" to me if all you do is read off the numbers from a digital display. – FumbleFingers Jan 26 '12 at 16:30
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The armed services (and their veterans) really have this engrained in my mind as such:

Rendezvous at 0600 [O-Six-Hundred] hours!

Drop point is X degrees north, at 1200 [Twelve-Hundred] hours!

Otherwise, where more precise in terms of declaring minutes, you can just split them and speak each unit of time individually:

Your meeting is at 1530 [Fifteen-Thirty] hours.

Your meeting is at 1812 [Eighteen-Twelve] hours.

The hours here, it might be argued, is redundant or even inaccurate, but that doesn't dictate the occurrences (or exclusion of such) in speech.

You could go the quarter to, half past route, but this is an interchangeable method of speaking time, not exclusive to verbalising time in its 24-hours form.

Since o'clock is an abbreviation of of the clock, I guess that technically you could speak in this manner in terms of 24-hours, such as: 15 o'clock. But this might sound a little peculiar to most. If we look at the definition of o'clock from TheFreeDictionary then it kind of indicates we would be playing it safer to use another form:

  1. Of or according to the clock: three o'clock.

  2. According to an imaginary clock dial with the observer at the center and 12 o'clock considered as straight ahead in horizontal position or straight up in vertical position. Used to indicate relative position: enemy planes at 10 o'clock.

  3. used after a number from one to twelve to indicate the hour of the day or night

  4. (Mathematics & Measurements / Navigation) used after a number to indicate direction or position relative to the observer, twelve o'clock being directly ahead or overhead and other positions being obtained by comparisons with a clock face

If we do decide to use the 24 o'clock approach, then it's just redundant, if nothing else; consider the note on relativity to the face / direction. Since, regardless of the numbers being bigger, we don't have to (necessarily) do any extra laps around the clock face to arrive at the specified location - but in cases where AM and PM might not be clearly implied, it could serve to do that.

Grant Thomas
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    I don't understand your examples. Take the fourth. Are you saying 1812 should be spoken as Eighteen Twelve hours? I don't say the word hours unless the minutes are zero (in which case I say hundred after the hours value). – FumbleFingers Jul 20 '11 at 16:19
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    @FumbleFingers: This is indeed the system the U.S. Military uses. There may be other English-speaking organizations that use the 24-hour clock, but are pronounced differently. – Peter Shor Jul 20 '11 at 17:37
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    @Peter Shor: oic. It sounds weird to me to hear hours spoken unless it was preceded by hundred, but I don't really do military time as such. I worked in the UK bus industry, where times were invariably 24-hour, but nobody wanted to sound like a squaddie. It was always just the numbers, with hundred instead of the minutes value if that was zero. – FumbleFingers Jul 20 '11 at 17:56
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    @FumbleFingers: The US Emergency Services (police/fire/paramedic) typically do as you describe. "The call came in at eighteen-twelve." – Lynn Dec 01 '11 at 23:21
  • The "hours" suffix, replacing "o'clock", seems to be a convention for indicating that the number is intended to be taken as 24-hour time. Arguably that should be obvious from the fact that the hour is greater than twelve, but... – keshlam Jul 19 '14 at 14:56
  • You could have met in 2010 on 20/10 at 2010. – Spehro Pefhany Jul 19 '14 at 15:26
  • Everything here is of course accurate, but I don’t like that it’s based entirely on American civil service conventions. It would seem weird to me to hear a civilian say “fifteen-thirty hours.” – gen-ℤ ready to perish Jul 25 '20 at 00:30
  • As I recall the time announcements from WWV just barge through it in formal English. For example, 2337 UTC is pronounced "twenty three hours, thirty seven minutes Coordinated Universal Time". – David42 Jan 24 '23 at 17:41
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When I lived in Japan, they generally used the 24-hour clock, but in speech they translated the hour on the fly - so 13:00 on the clock was "ichi-ji" (one o'clock).

The Raven
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    That's quite common in German as well: most clocks show use a 24-hour display, but in spoken language you're still talking about "Ein Uhr" (one o'clock). – Joachim Sauer Nov 22 '11 at 07:35
  • In Portugal, we can also say 'São 13 (horas).' (It's thirteen) or 'É uma (hora).' (It's one). – SC for reinstatement of Monica Jun 08 '13 at 12:28
  • @JoachimSauer Same in Sweden but we don't say PM or AM. If there is any confusion we say "in the afternoon" or use the 24 notation, like "seventeen forty-five". – Prof. Falken Oct 23 '13 at 17:58
  • +1. This is the only common way I've ever heard it done by anyone who lives in a country where 24-hour time is the norm. Only use hours greater than 12 when specifying an exact time: it's a quarter past six, but it's 18:17. – Janus Bahs Jacquet Jul 23 '14 at 08:29
  • @JanusBahsJacquet in French, at least in Europe, it seems more common to say "dix-huit heures dix-sept" than "six heures dix-sept." – phoog Mar 28 '24 at 13:22
  • @phoog Yup, that’s exactly what I meant. It would be a lot less common to say, “Il est dix-huit heures et demie” than “Il est six heures et demie”, but more common to say, “Il est dix-huit heures dix-sept” than “Il est six heures dix-sept” (unless you mean 06:17 in the morning, of course). In some languages (including English), I would say it’s in fact completely impossible to use at least some non-numeric forms with numbers above 12 – ‘half past eighteen’ sounds not only odd to me, but utterly impossible. – Janus Bahs Jacquet Mar 28 '24 at 13:32
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I know you can't hear them in the USA but take these examples from British railway station announcements.

AM
0733  Oh seven thirty-three
0800  Oh eight hundred
0905  Oh nine oh five
1012  Ten twelve

PM
1300  Thirteen hundred
1706  Seventeen oh six
2359  Twenty-three fifty-nine
JJJ
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Eric
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According to the BBC World Service, the correct notation is,

Fifteen hours GMT

They used to say fifteen-hundred hours, but they've dropped that now.

TRiG
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Just in case you are interested in how 24-hour format used in other countries. I am Russian, living in Russia, and 24-hour clock is pretty common here. Here is some facts about it:

  1. Beside the military and such (like police, navigation services etc.), it is common in TV schedules, which means every Russian uses it.

  2. We always use dividers between hours and minutes, although there isn't a single accepted divider. The most common is a full stop, like 23.12 for 11:12pm. Hyphen is also used: 23-12. Since around 1980's, when imported clocks (mostly Chinese at that time) became common, the colon have been widely used, too: 23:12.

  3. Saying aloud (variants):

    • "twenty-three hours, twelve minutes". If there are leading zeroes in hours and minutes, they are ignored: 03:05am is pronounced "three hours, five minutes". Usually you hear it in TV announcments of coming programs or events; also in other formal speaking.
    • "twenty three, twelve". Leading zeroes are only ignored with hours: 03:05pm is "three, oh-five". Casual use.
    • in both cases, if the minutes are "00", they are omitted: "at 11pm" will be "at twenty three (hours)".

Why the 24-hour format is more common in Russia than in English-speaking countries is because we do not have the short and convenient "am/pm" modifier. Our 12-hour am/pm equivalents are "utrah" (=of the morning), "dnyah" (of the day), "vehchera" (of evening/early night) and "nAWchi" (of night/small hours). Wrong use of such a modifier can produce a humorous effect. E.g., if you say "forteen of the morning", it's a fun way to imply that you are a night person, and 2pm is, like, still morning for you.

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You can still simply say what it represents. For example, for this one:

15:45

You could say "A quarter to 4."

See the Criticism and practical problems section in wikipedia.

mipadi
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Alenanno
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  • What if it's 15:22? Do I say "three twenty-two"? – Nathan G. Jul 20 '11 at 15:51
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    Yes, the point is that you write the time as 24-hour but you read it as it was 12-hour. – Alenanno Jul 20 '11 at 15:55
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    @Nathan G. If you're doing a 24-hour clock you say fifteen, not three, obviously. – FumbleFingers Jul 20 '11 at 16:11
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    @FumbleFingers: It's not that obvious, actually. You can choose to say "fifteen" but there's no problem in using the 12-hour system when reading it. – Alenanno Jul 20 '11 at 16:12
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    @Alenanno: But OP specifically said he wants to speak in 24-hour notation. I'm not saying there's anything wrong with three o'clock, but it's obviously not a 24-hour value (inviting confusion with 3am, the avoidance of which is surely the rationale for 24-hour notation in the first place). – FumbleFingers Jul 20 '11 at 16:30
  • @FumbleFingers: He said how can you read it when it's written in 24-hour notation, otherwise the questions makes no sense. The confusion stays when I say the time and you can't see the time here. I mean in chat for example. If we're both in the street and I tell you "it's three twenty-two", you will know it's not AM. – Alenanno Jul 20 '11 at 17:07
  • @Alenanno: I guess it depends how you interpret OP's wording. It makes sense to me to assume he's asking "how do you say times if you want to speak in 24-hour notation", otherwise I can't see the point of mentioning the digital display in the first place. Without that, they're all just "times". – FumbleFingers Jul 20 '11 at 17:16
  • @FumbleFingers: I guess this will be endless unless we ask the OP :P – Alenanno Jul 20 '11 at 17:19