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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?

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There is no reason you cannot say "fifteen o'clock," except when it's not 15:00. –  kiamlaluno 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
    
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.) –  kiamlaluno 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
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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 Answers 7

up vote 15 down vote accepted

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.

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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 1 '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 at 14:56

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.

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1  
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
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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
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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 9:20
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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
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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

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).

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+1 for confirming it's not just a quirk of Brits! –  FumbleFingers Jul 20 '11 at 20:07
    
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 7:35
    
+1 because I do this as as well. Also, I'm Canadian. –  Joe Z. Feb 8 '13 at 19:00
    
In Portugal, we can also say 'São 13 (horas).' (It's thirteen) or 'É uma (hora).' (It's one). –  Sara Costa Jun 8 '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

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.

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What if it's 15:22? Do I say "three twenty-two"? –  Nathan G. Jul 20 '11 at 15:51
    
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
    
@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

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.

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BBC World Service has used "fifteen hours" for many years. It's one of the antique features I rather liked. –  Andrew Leach Apr 11 '13 at 9:42

I know you can't hear them in the USA but take exaples 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
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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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