12-hour clock
The 12-hour clock is a way of dividing the 24 hours of the day into two sections. The two halves are called ante meridiem (a.m.) and post meridiem (p.m.). Both names are from Latin and Latin: ante meridiem, means "before midday" and Latin: post meridiem means "after midday".[1]
Each period has 12 hours and are numbered 1 or 0 to 12 or 11. Time from midnight to noon is a.m. and from noon to midnight p.m. The table at right shows how it relates to the 24-hour clock.
| 24-hour clock | 12-hour clock |
|---|---|
| 24:00/0:00 | 12:00 AM, midnight
(start of day) |
| 01:00 | 1:00 AM |
| 02:00 | 2:00 AM |
| 03:00 | 3:00 AM |
| 04:00 | 4:00 AM |
| 05:00 | 5:00 AM |
| 06:00 | 6:00 AM |
| 07:00 | 7:00 AM |
| 08:00 | 8:00 AM |
| 09:00 | 9:00 AM |
| 10:00 | 10:00 AM |
| 11:00 | 11:00 AM |
| 12:00 | 12:00 PM (noon) |
| 13:00 | 1:00 PM |
| 14:00 | 2:00 PM |
| 15:00 | 3:00 PM |
| 16:00 | 4:00 PM |
| 17:00 | 5:00 PM |
| 18:00 | 6:00 PM |
| 19:00 | 7:00 PM |
| 20:00 | 8:00 PM |
| 21:00 | 9:00 PM |
| 22:00 | 10:00 PM |
| 23:00 | 11:00 PM |
| 24:00/0:00 | 12:00 AM, midnight
(end of day) |
The 12-hour time is common in several English-speaking countries and former British colonies (such as the United Kingdom, the United States, the English speaking parts of Canada or India), as well as a few other countries. There is no widely accepted convention for how midday and midnight should be represented: in English-speaking countries, "12 p.m." means 12 o'clock noon, while "12 a.m." means 12 o'clock midnight.[2][3][4]
12-hour Clock Media
Exeter Cathedral Astronomical Clock, showing the double-XII numbering scheme
Typical digital 12-hour alarm clock indicating p.m. with a dot to the left of the hour
References
- ↑ "Time". The New Encyclopædia Britannica 28. (1986). 660 2a.
"Time". Encyclopædia Britannica. Encyclopædia Britannica Online Library Edition. “The use of AM or PM to designate either noon or midnight can cause ambiguity.” - ↑ "Is noon 12 am or 12 pm?". Royal Museums Greenwich. Retrieved 2023-01-26.
- ↑ "U.S. Government Printing Office Style Manual - Chapter 12 - Numerals". govinfo.gov. Retrieved 2023-01-27.
- ↑ "time of day, elapsed time". Resources of the Language Portal of Canada. 2020-10-22. Retrieved 2023-01-27.