Military (24-Hour) Time Converter

Converting by hand

1. 12-hour to 24-hour: AM hours are unchanged, except 12 AM which is 00. PM hours add 12, except 12 PM which stays 12. So 3:15 PM is 15:15 and 12:40 AM is 00:40.
2. 24-hour to 12-hour: 00 becomes 12 AM, 01-11 are AM, 12 is 12 PM, and 13-23 subtract 12 and are PM. So 21:05 is 9:05 PM.
3. Military style writes four digits and no colon: 0905, 2105 “hours”.

24-hour time chart

Worked examples

Where 24-hour time is used

Many hospitals, emergency services, the armed forces, airlines, transportation and manufacturing plants schedule in 24-hour time because it removes AM/PM mistakes. Time clocks in those settings often display 24-hour times, so converting is a routine skill for time card checking. Use the time card calculator, which accepts 24-hour entries directly (type 1730 or 17:30).

Writing and saying military time

In 24-hour notation the day runs from 0000 (midnight) to 2359. Four digits are written without a colon: the first two are hours, the last two are minutes. 0600 is six o'clock in the morning, 1200 is noon, 1800 is six in the evening and 2359 is one minute before midnight. In speech, times are commonly said digit-pair by pair: 0830 is “oh-eight-thirty”, 1700 is “seventeen hundred”. The convention differs a little between organisations, so follow your workplace's style.

Using 24-hour time on a time card

Time clocks, rosters and shift schedules in hospitals, factories, airlines and public safety services are often in 24-hour time. Our calculators accept it directly: type 1730 or 17:30 and it is read as 5:30 pm. For a shift that crosses midnight, enter the real end time (for example 0630 after a 2200 start). The time card calculator then counts the shift as ending the next day.

A common mistake is to subtract military times as if they were decimals: 1530 minus 0700 is not 830 minutes. Convert to hours and minutes first: 15:30 minus 07:00 is 8 hours 30 minutes.

Conversion examples

Notice the two traps: 12:00 PM is noon (stays 12) and 12:01 AM is just after midnight (becomes 00:01). Most mistakes come from these two cases.

Shift lengths in military time

Subtract the start from the end after converting to hours and minutes. For 1900 to 0300: 03:00 is earlier than 19:00 so add 24 hours: 27:00 − 19:00 = 8:00. For 0545 to 1415: 14:15 − 05:45 = 8 hours 30 minutes. For 2230 to 0600: 30:00 − 22:30 = 7 hours 30 minutes. If you subtract the four-digit numbers directly (1415 − 545 = 870), the result is meaningless, because the last two digits are minutes that roll over at 60.