AM vs PM: What They Mean
AM means before midday and PM means after it. Here is how it works, and the noon and midnight trap.
The short answer
AM stands for ante meridiem, Latin for "before midday". PM stands for post meridiem, "after midday". AM covers midnight to just before noon; PM covers noon to just before midnight.
12 AM and 12 PM
This is where most mix-ups happen. 12:00 PM is noon (midday) and 12:00 AM is midnight at the start of a day. To avoid confusion on tickets and invites, write "12 noon" or "12 midnight", or use 24-hour time.
| 12-hour | 24-hour | Meaning |
|---|---|---|
| 12:00 AM | 00:00 | Midnight |
| 1:00 AM | 01:00 | Night |
| 6:00 AM | 06:00 | Morning |
| 12:00 PM | 12:00 | Noon |
| 1:00 PM | 13:00 | Afternoon |
| 6:00 PM | 18:00 | Evening |
| 11:59 PM | 23:59 | Last minute of the day |
Converting to 24-hour time
- From 1:00 AM to 11:59 AM, the hours are the same: 9:30 AM is 09:30.
- From 1:00 PM to 11:59 PM, add 12: 5:00 PM is 17:00.
- 12:xx AM becomes 00:xx, and 12:xx PM stays 12:xx.
Need a quick answer? Use the military time converter.
Questions
Is 12 PM noon or midnight?
12 PM is noon. 12 AM is midnight at the start of the day.
What does AM stand for?
Ante meridiem, Latin for "before midday".
Do all countries use AM and PM?
No. Most of the world writes times on the 24-hour clock, especially in timetables. The 12-hour clock with AM and PM is common in the US, UK, Canada, Australia, India and the Philippines.
By the TimeNowTools team · Last reviewed 18 October 2026