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Military Time

2010 December 4

Military time is an unambiguous, concise method of expressing time used by the military, emergency services (law enforcement, firefighting, paramedics), hospitals, and other entities. The following sections provide a detailed description of the difference between regular and military time, how military time is written, and several time conversion examples.

Regular versus Military Time

The main difference between regular and military time is how hours are expressed. Regular time uses numbers 1 to 12 to identify each of the 24 hours in a day. In military time, the hours are numbered from 00 to 23. Under this system, midnight is 00, 1 a.m. is 01, 1 p.m. is 13, and so on.

Regular and military time express minutes and seconds in exactly the same way. When converting from regular to military time and vice versa, the minutes and seconds do not change.

Regular time requires the use of a.m. and p.m. to clearly identify the time of day. Since military time uses a unique two-digit number to identify each of the 24 hours in a day, a.m. and p.m. are unnecessary.

The following table summarizes the relationship between regular and military time.

Regular Time Military Time Regular Time Military Time
Midnight 0000 Noon 1200
1:00 a.m. 0100 1:00 p.m. 1300
2:00 a.m. 0200 2:00 p.m. 1400
3:00 a.m. 0300 3:00 p.m. 1500
4:00 a.m. 0400 4:00 p.m. 1600
5:00 a.m. 0500 5:00 p.m. 1700
6:00 a.m. 0600 6:00 p.m. 1800
7:00 a.m. 0700 7:00 p.m. 1900
8:00 a.m. 0800 8:00 p.m. 2000
9:00 a.m. 0900 9:00 p.m. 2100
10:00 a.m. 1000 10:00 p.m. 2200
11:00 a.m. 1100 11:00 p.m. 2300

What about Military Minutes?

Regular and military time use the same number of minutes per hour and they use minutes in exactly the same way. Military minutes do not exist and there is is no need to convert minutes when going back and forth between the two time systems.

People occassionally encounter time written in a format that appears to use minutes larger than 59 (for example 7:82 or 7.82). Time written in this manner is being expressed in decimal hours (hours and hundreths of hours), not military time. Converting from decimal hours to hours and minutes is a different issue than converting between regular and military time.

Is Midnight 2400 or 0000?

The question sometimes arises whether midnight is written as 2400 or 0000. Military and emergency services personnel refer to midnight both ways. However, digital watches and clocks that display time in a 24-hour format and computer equipment treat midnight as the start of a new day and express it as 0000.

Writing Military Time

Different professions and types of organizations write military time differently. The military, emergency services and hospitals usually write military time as hours and minutes without a colon and often add the word "hours" afterward. The format is:

hoursminutes

Example: 1331 or 1331 hours

When expressing time down to the second, they insert a colon between the minutes and seconds using the format

hoursminutes:seconds

Example: 1331:42 or 13:31:42 hours

In science and engineering, colons are usually inserted between the hours, minutes, and seconds. The formats used to express time are:

hours:minutes

Example: 13:31 and

hours:minutes:seconds

Example: 13:31:42

Sources of Military Time

Two sources of military time are digital wrist watches and 24-hour clocks. Many digital watches provide the option of displaying the time in either regular or military format. Switching back and forth is usually done by pressing a button labeled "12/24" or something similar.

Various firms manufacture 24-hour clocks. One such company is MFJ Enterprises (www.mfjenterprises.com), a radio equipment manufacturer in Mississippi. They offer a wide selection of reasonably priced 24-hour clocks.

Time Conversion Examples

Military to Regular Time

Assume that an event occurs at 0001 military time. To convert this to regular time, separate the hours from the minutes. The hours are shown below in red:

0001

Look up the hour digits (00) in the conversion table (above). The table shows that 00 hours in military time is 12 a.m. in regular time.

The next two digits (01) represent the minutes past the hour. Since military time and regular time use minutes in exactly the same way, no conversion is required.

Thus, 0001 military time translates to 12:01 a.m. or one minute past midnight regular time.

Regular to Military Time

Assume that you want to convert 1:17:42 p.m. (forty-two seconds past 1:17 in the afternoon) to military time. Using the above conversion table, we see that this translates to 13:17:42 or 1317:42 military time (depending which style you use to write it).

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