The difference between 12-hour and 24-hour time
24-hour format (also called military or European time) counts hours from 00 to 23 with no need to specify morning or evening — 14:30 unambiguously means 2:30 PM. 12-hour format repeats the numbers 1 through 12 twice a day, and needs AM or PM to tell the two halves apart.
| 24-hour | 12-hour |
|---|---|
| 00:00 | 12:00 AM (midnight) |
| 12:00 | 12:00 PM (noon) |
| 13:00 | 1:00 PM |
| 23:45 | 11:45 PM |
Common mistakes when converting by hand
- Mixing up midnight and noon: 12:00 AM is midnight (00:00 in 24-hour format), while 12:00 PM is noon (12:00 in 24-hour format) — the reverse of what many people assume.
- Forgetting to subtract 12 for afternoon hours: converting 24-hour to 12-hour, subtract 12 from any hour between 13 and 23 to get the correct 12-hour number (e.g. 15 − 12 = 3 PM).
- Getting confused at exactly 12: 12 noon in 24-hour format stays 12 (don't subtract 12 from it), unlike every other afternoon hour.
Frequently asked questions
What does 00:00 mean in 12-hour format?
It means midnight, written as 12:00 AM in 12-hour format.
What does 12:00 noon mean in 24-hour format?
It stays 12:00 in 24-hour format (no change at that exact moment), and is written as 12:00 PM in 12-hour format.
Which countries typically use 24-hour time?
24-hour format is widely used in most European, Arab and Asian countries for official contexts, while the United States and a few other countries prefer 12-hour format in everyday use.
Are the times I enter stored anywhere?
No, the conversion happens entirely in your browser and nothing is sent to a server.
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