AM and PM – Meaning and Relation with 24-Hour clock

AM and PM are Latin terms for the hours of the day. Ante meridiem and Post meridiem are shortened phrases that imply before noon or midday and afternoon or midday, respectively. AM denotes the first 12-hour period, which runs from midnight to noon, and PM denotes the second 12-hour period, which runs from midday to midnight.

AM and PM

Hours, minutes, and seconds are the units of measurement for time. There are 24 hours in a day, 60 minutes in an hour, and 60 seconds in a minute. 8:20, for example, denotes 8 hours and 20 minutes. There are two methods to show time. The first is through a 24-hour clock, while the second is via an AM-PM clock. The abbreviation ‘AM’ stands for ante meridiem (time between midnight and 11.59 a.m.) and ‘PM’ stands for post-meridiem (time after the meridian line has crossed the Sun) (after the meridian line has crossed the Sun or the time between noon and 11.59 at night).

The 12-hour clock system uses the numerals 1 to 12 followed by am or pm to represent all 24 hours of the day. 5 a.m. is early in the morning, and 5 p.m. is late in the afternoon; 1 a.m. is after midnight, and 11 p.m. is before midnight. AM, am, a.m., or A.M. is the abbreviation for ante meridiem, whereas PM, pm, p.m., or P.M. is the abbreviation for post meridiem.

Convert AM PM Clock to a 24-Hour Clock

By removing 12 hours from the first hour of the day, we may convert an AM-PM clock to a 24-hour clock (midnight to 12:59 a.m.).

ExampleConversion to 24-hour clockTips for conversion
12:00 AM12:30 AM10:00 AM0:000:3010:00Between 1:00 am and 11:59 am, the hours and minutes remain the same.
3:17 PM11:49 PM10:00 PM15:1723:4922:00For the time range between 1:00 PM and 11:59 PM, add 12 hours.

Convert a 24-Hour Clock to AM-PM Clock

By adding 12 hours from the first hour of the day (0:00 / midnight to 0:59) and AM to the time, a 24-hour clock may be converted to an AM-PM clock.

ExampleConversion to AM-PM clockTips for conversion
0:401:553:4512:40 AM1:55 AM3:45 AMFrom 1:00 to 11:59, add AM to the time

16:5521:4513:00 

4:55 PM8:45 PM1:00 PM 
Add PM to the time for intervals between 13:00 and 23:59 after subtracting 12 hours

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