# 24-hour clock

| 24-hour clock | 12-hour clock | Military time | Period |
| --- | --- | --- | --- |
| 00:00 | 12:00 AM Midnight | 0000 LT | Postmidnight |
| 01:00 | 1:00 AM | 0100 LT |
| 02:00 | 2:00 AM | 0200 LT |
| 03:00 | 3:00 AM | 0300 LT |
| 04:00 | 4:00 AM | 0400 LT |
| 05:00 | 5:00 AM | 0500 LT |
| 06:00 | 6:00 AM | 0600 LT | Morning |
| 07:00 | 7:00 AM | 0700 LT |
| 08:00 | 8:00 AM | 0800 LT |
| 09:00 | 9:00 AM | 0900 LT |
| 10:00 | 10:00 AM | 1000 LT |
| 11:00 | 11:00 AM | 1100 LT |
| 12:00 | 12:00 PM Midday Noon | 1200 LT | Afternoon |
| 13:00 | 1:00 PM | 1300 LT |
| 14:00 | 2:00 PM | 1400 LT |
| 15:00 | 3:00 PM | 1500 LT |
| 16:00 | 4:00 PM | 1600 LT |
| 17:00 | 5:00 PM | 1700 LT |
| 18:00 | 6:00 PM | 1800 LT | Evening |
| 19:00 | 7:00 PM | 1900 LT |
| 20:00 | 8:00 PM | 2000 LT |
| 21:00 | 9:00 PM | 2100 LT |
| 22:00 | 10:00 PM | 2200 LT |
| 23:00 | 11:00 PM | 2300 LT |

A world map that shows if time is normally written as 12-hour or 24-hour in each country  Writes in 24-hour normally  Writes in both formats by different people  Writes in 12-hour normally
The **24-hour clock** is a method of telling the time in which the civil day runs from midnight until next midnight.

The following numbers (used once in the same civil day) of hours are: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22 and 23, without **AM** nor **PM**.

This system is also referred to (only in the United States and the English speaking parts of 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**. Also, the international standard notation of time (ISO 8601) is based on this format.

## Particulars

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 (called a leading zero); e.g. 09:07. Under the 24-hour clock system, the day begins at midnight, 00:00. The last minute of the day begins at 23:59 and ends at 24:00, which is the same as 00:00 of the following day. This means that "Tuesday at 24:00" and "Wednesday at 00:00" are the same time. Because of this, 12:00 is always noon.

Advantages over the 12-hour clock system:

* Less confusion between morning and evening.
* 12:00 is always midday.

## Application

### Regional

In many African, Asian, European and Latin American countries people use it to write the time. Many people use it in speaking. Many digital wristwatches and clocks can display the time of day using the 24-hour clock.

### Military

The U.S. military prefers not to say 24:00 - they do not like to have two names for the same thing, so they always say "23:59", which is one minute before midnight.

A 24-hour clock face
24-hour clock time is used in computers, by the militaries, for public safety, and in transport.

### Railway

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

## Related pages

* Time
* Clock
* Space
* Physics
* Spacetime
* Kinematics
* Radioactivity
* Albert Einstein
* Atomic physics
* General Relativity
* Erwin Schrödinger
* Classical mechanics
* Quantum mechanics
* Unit of Measurement
* International System of Units (SI units)