Time & Dates

What Is the 24-Hour Clock?

The 24-hour clock expresses time as the number of hours since midnight, from 00:00 to 23:59, instead of repeating 1 to 12 with AM and PM. It is the standard time format in most countries and is called military time in the United States, where it is often written without a colon, such as 1500 for 3:00 PM.

How to Convert

For times from 1:00 PM to 11:59 PM, add 12 to the hour: 3:00 PM becomes 15:00. Midnight is 00:00 and noon is 12:00.

Why It Is Used

It removes the ambiguity between AM and PM, which is why it is used in aviation, healthcare, transport timetables, and computing.

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Put 24-Hour Clock (Military Time) into practice with these free calculators — no sign-up, nothing stored.

🪖 Military Time Converter Convert between 12-hour and 24-hour (military) time instantly. Calculate → 🌍 Time Zone Converter Convert any date and time between world time zones, with daylight saving time handled automatically. Calculate →

🔗 Related Terms

Coordinated Universal Time (UTC) Daylight Saving Time (DST)

More Time & Dates Terms

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Last updated: September 27, 2026. This definition is for general educational purposes only. It is not financial, investment, tax, legal, or medical advice, and it does not recommend any product or course of action. For decisions about your own situation, consult a qualified professional.