24-hour clock

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24-hour clock 12-hour clock
00:00 12:00 midnight
01:00 1:00 am
02:00 2:00 am
03:00 3:00 am
04:00 4:00 am
05:00 5:00 am
06:00 6:00 am
07:00 7:00 am
08:00 8:00 am
09:00 9:00 am
10:00 10:00 am
11:00 11:00 am
12:00 12:00 noon
13:00 1:00 pm
14:00 2:00 pm
15:00 3:00 pm
16:00 4:00 pm
17:00 5:00 pm
18:00 6:00 pm
19:00 7:00 pm
20:00 8:00 pm
21:00 9:00 pm
22:00 10:00 pm
23:00 11:00 pm
24:00 12:00 midnight

The 24-hour clock is a method of telling the time in which the day runs from midnight to midnight and is divided into 24 hours, numbered from 0 to 23. This system is also referred to (only in the US and Canada) as military time or (only in the United Kingdom and now very rarely) as continental time. In some parts of the world, it is called railway time.

A time in the 24-hour clock is written in the form hours:minutes (for example, 01:23), or hours:minutes:seconds (01:23:45). Numbers under 10 have a zero in front; e.g. 09:07. Under the 24-hour clock system, the day begins at midnight, 00:00, and the last minute of the day begins at 23:59 and ending at 24:00, which is identical to 00:00 of the following day. 12:00 can only be mid-day and midnight is 24:00 or 00:00 whichever you prefer. The army prefers not to use 24:00 - they do not like there to be two names for the same thing so they always say "23:59", which is one minute before midnight.

To convert between the 12-hour clock and the 24-hour clock, use the table to the right.

24-hour clock time is used in computers, military, public safety, and transport. In many Asian, European and Latin American countries people use it to write the time. Many French, Italian and Romanian people use it in speaking.

Many models of digital wristwatches and clocks are available that display the time of day using the 24-hour clock.

In railway timetables 24:00 means the end of the day. For example, a train due to arrive at a station during the last minute of a day arrives at 24:00; but trains which depart during the first minute of the day go at 00:00.

To write shop opening hours until midnight use, for example, "00:00–24:00", "07:00–24:00".

Advantages over the 12-hour system:

  • Fewer confusions between morning and evening; e.g. 7 o'clock.
  • People forget if midday is 12 am or 12 pm.
  • It is easier to calculate duration. From 10:30 am till 3:30 pm is 5 hours. From 10:30 till 15:30 indicates this better.