What this calculator does
Turn a regular AM/PM time into military time, or military time back into AM/PM. Military time numbers the hours of the day from 00 to 23, instead of counting 1 to 12 twice with AM and PM. It's written as four digits with no colon. So 7:30 in the evening is 1930, and a minute after midnight is 0001. Hospitals, the armed forces, airlines, emergency services and public transport use it. So does most of the world outside North America. It leaves no doubt about morning or evening.
This converter works both ways. Give it a 12-hour time with AM or PM. You'll get the four-digit military time, the 24-hour time with a colon, and the usual way to say it out loud. Or give it a military time, and you'll get the 12-hour time. A chart of every hour of the day is included for quick lookups.
Where it's used
Why this math matters outside the classroom:
- Reading 24-hour times. The time 1530 is 3:30 p.m., found by subtracting 12 from the hour.
- Just after midnight. The time 0015 is 12:15 a.m., since hour 00 is the midnight hour.
- Hospitals and shift work. Nurses and dispatchers log events in 24-hour time so morning and evening are never confused.
- Travel schedules. Travelers read train and flight times printed in 24-hour form and convert them to a 12-hour clock.
How to use it
- Choose the direction: 12-hour to military, or military to 12-hour.
- For 12-hour time, enter the hour (1 to 12) and the minute (0 to 59), and choose AM or PM.
- For military time, type the four digits, such as 0730 or 2215. Three digits (930) or a colon (21:15) work too.
- Read the converted time and how to say it. Use the chart below for any other whole hour.
What the inputs mean
- Hour
- The hour as shown on a 12-hour clock. Midnight and noon are both 12.
- AM or PM
- AM runs from midnight to just before noon. PM runs from noon to just before midnight.
- Military time
- Two digits for the hours (00 to 23), then two digits for the minutes. 2400 also works, as midnight at the end of a day.
Formula and method
12 AM → hour 00; 1 to 11 AM → same hour 12 PM → hour 12; 1 to 11 PM → hour + 12 military hour 00 → 12 AM; 01 to 11 → AM; 12 → 12 PM; 13 to 23 → hour − 12, PM
The only math is adding or taking away 12 for afternoon and evening hours. The arrow (→) means "becomes". The two hours called 12 are the exceptions. 12 AM is the first hour of the day, so it becomes 00. 12 PM is noon, so it stays 12.
Military time always uses two digits for the hours and two for the minutes. A zero at the front is kept, so 6:05 AM is 0605, not 605.
Worked example
Convert 7:45 PM to military time. Then convert 0015 back to 12-hour time.
- 7:45 PM is a PM hour from 1 to 11, so add 12: 7 + 12 = 19.
- Write the hour and minutes as two digits each, with no colon: 1945.
- For 0015, the hours are 00 and the minutes are 15.
- Hour 00 is the midnight hour, which a 12-hour clock calls 12 AM.
Result: 7:45 PM is 1945, said "nineteen forty-five hours". 0015 is 12:15 AM, a quarter past midnight.
Understanding the result
The spoken form follows a common pattern: say the hours as one number, then the minutes as one number. Whole hours end in "hundred", so 1400 is "fourteen hundred hours". A zero at the front is said as "zero", so 0730 is "zero seven thirty". Some services say "oh" instead of "zero", and both are understood.
The 24-hour time with a colon (19:45) means the same as military time (1945). The colon form is standard on timetables and phones. The four-digit form is the military and medical habit.
To read a military time quickly, take 12 away from any hour above 12. 1700 minus 12 hours is 5 PM.
Assumptions and limitations
- Times are local clock times, with no time zone attached.
- Hours run from 00 to 23, and minutes from 00 to 59.
- Seconds aren't converted.
- It doesn't add military time zone letters (such as Z for UTC, often called Zulu time). Use the time zone converter to change zones.
- 2400 is read as midnight at the end of the day. Some organizations avoid it and use 2359 or 0000 instead.
Frequently asked questions
What is 12 AM in military time?
12 AM is midnight, the start of the day, so it's 0000. 12:30 AM is 0030. This is the one people most often get wrong. The 12 seems to suggest 1200, but 1200 is actually noon.
Is 2400 the same as 0000?
They're the same moment, seen from two different days. 2400 marks the end of one day and 0000 the start of the next. So a shift might run from 1600 to 2400. Many systems only accept 0000, and the calculator treats 2400 as 12:00 AM.
How do I convert military time to standard time?
If the hours are 13 or more, take away 12 and add PM, so 1530 becomes 3:30 PM. If the hours are 12, keep 12 and add PM. If they're 00, it's 12 AM. Anything from 01 to 11 is AM, with the zero at the front dropped.
Why do the military and hospitals use 24-hour time?
Each time of day gets its own number. So there's no AM or PM to mishear, or to leave off a chart or order. That matters when one person logs a medicine time, a flight or a move, and someone else on another shift reads it.
How this calculator is checked
Method: Standard 24-hour clock notation (as in ISO 8601), written without the colon in military style; 12-hour conversion by the ±12-hour rule. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.
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