What do AM and PM mean?
AM means ante meridiem, "before midday": the hours from midnight to 11:59 in the morning. PM means post meridiem, "after midday": noon to 11:59 at night. Noon is 12 PM and midnight is 12 AM.
Right now, on your device's clock, it's
AM and PM at a glance
| 24-hour time | 12-hour time | Part of the day |
|---|---|---|
| 00:00 | 12:00 AM | Midnight |
| 01:00 | 1:00 AM | Night |
| 02:00 | 2:00 AM | Night |
| 03:00 | 3:00 AM | Night |
| 04:00 | 4:00 AM | Early morning |
| 05:00 | 5:00 AM | Early morning |
| 06:00 | 6:00 AM | Morning |
| 07:00 | 7:00 AM | Morning |
| 08:00 | 8:00 AM | Morning |
| 09:00 | 9:00 AM | Morning |
| 10:00 | 10:00 AM | Morning |
| 11:00 | 11:00 AM | Morning |
| 12:00 | 12:00 PM | Noon |
| 13:00 | 1:00 PM | Afternoon |
| 14:00 | 2:00 PM | Afternoon |
| 15:00 | 3:00 PM | Afternoon |
| 16:00 | 4:00 PM | Afternoon |
| 17:00 | 5:00 PM | Afternoon (early evening) |
| 18:00 | 6:00 PM | Evening |
| 19:00 | 7:00 PM | Evening |
| 20:00 | 8:00 PM | Evening |
| 21:00 | 9:00 PM | Night |
| 22:00 | 10:00 PM | Night |
| 23:00 | 11:00 PM | Night |
Why 12 AM and 12 PM confuse people
On a 12-hour clock the hour after 11 is 12, not 0, so the "12" hour belongs to the half of the day that's just starting. 12:30 AM is half an hour after midnight; 12:30 PM is half an hour after noon. Airlines, the military and most computers avoid the problem entirely with 24-hour time, where midnight is 00:00 and noon is 12:00. Convert any time with the military time converter.
Where the words come from
The Latin meridies means midday, the moment the Sun crosses the meridian, the imaginary north–south line overhead. Romans split the day into before and after that moment, and the abbreviations a.m. and p.m. have been used in English since the 1600s. Both "AM" and "a.m." are correct; newspapers in the US usually write "a.m." and "p.m." in lowercase with periods.
Questions people ask
What do AM and PM stand for?
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.
Is noon AM or PM?
Noon is 12:00 PM. (More on is noon AM or PM.) One minute later is 12:01 PM. Strictly speaking noon is neither before nor after midday, so many style guides prefer to write "12 noon" to avoid confusion.
Is midnight AM or PM?
Midnight is 12:00 AM (see is midnight AM or PM), the start of the new day. 11:59 PM is the last minute of the day before. To avoid mix-ups, write "12 midnight" or use 24-hour time (00:00).
What time is noon?
Noon is 12:00 PM, the middle of the day: 12:00 in 24-hour time.
Is 12 AM morning or night?
12 AM is midnight, so it's the very start of the morning of the new day. If an event is at "12 AM on Friday", it's at midnight between Thursday night and Friday morning.
What time is "this afternoon"?
Afternoon runs from 12 PM (noon) until about 5 or 6 PM, when evening begins. Morning is from midnight (or sunrise) to noon, and evening usually runs to about 9 PM, then night.
Is it AM or PM at 12 noon?
PM. 12 noon is written 12:00 PM, and 12 midnight is 12:00 AM.
What time does night start?
There's no official time, but night is usually counted from about 9 PM, or from sunset, until sunrise. Evening runs roughly 6 to 9 PM.
What is noon?
Noon is 12:00 PM, the middle of the day. Solar noon, when the Sun is highest, can be up to an hour or more away from 12:00 on the clock because of time zones and daylight saving.
Do all countries use AM and PM?
No. Most of the world writes times in 24-hour format, especially in writing and timetables. The 12-hour clock with AM and PM is standard in the US, Canada, the UK in speech, Australia, India, the Philippines and several other countries.
Related: 12-hour clock · 24-hour clock · military time · how long until noon · how long until midnight