From 12:01 pm to 12:59 pm, do nothing | 12-hour clock at noon: 12 am or 12 pm? Imagine being asked to pick up a friend at the airport at 12:00 am on April 13 |
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The Egyptians are thought to be responsible for dividing the day into 24 equal parts | Midnight Confusion Another source of confusion is the lack of a date designator in the 12-hour system, making it impossible to logically identify a correct moment in time when only a date and 12:00 am midnight is provided |
Your friend could ask you to be at the airport at 12:01 am on April 13 or, if the following midnight is meant, at 11:59 pm on April 13.
17To convert am or pm time to the 24-hour format, use these rules:• From midnight to 12:59 am, subtract 12 hours | For example, at 23:00, 23 hours have passed since the beginning of the current day |
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From 1:00 pm to midnight, add 12 hours | Alternatively, the 24-hour format could be used |
From 12:00 to 12:59, just add pm after the time.
4To avoid any confusion when referring to the precise moment of noon or midnight, we recommend using the designations 12 noon and 12 midnight instead | For example, 5 am is early in the morning, and 5 pm is late in the afternoon; 1 am is one hour after midnight, while 11 pm is one hour before midnight |
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Starting at midnight, hours are numbered from 0 to 24, removing the need for designations like am and pm | For example, the moment of midnight occurs precisely 12 hours after noon on the previous day and 12 hours before noon on the following day |
Time Formats 12-hour 24-hour 12:00 midnight 0:00 beginning of the day 12:01 am 0:01 1:00 am 1:00 2:00 am 2:00 3:00 am 3:00 4:00 am 4:00 5:00 am 5:00 6:00 am 6:00 7:00 am 7:00 8:00 am 8:00 9:00 am 9:00 10:00 am 10:00 11:00 am 11:00 12:00 noon 12:00 12:01 pm 12:01 1:00 pm 13:00 2:00 pm 14:00 3:00 pm 15:00 4:00 pm 16:00 5:00 pm 17:00 6:00 pm 18:00 7:00 pm 19:00 8:00 pm 20:00 9:00 pm 21:00 10:00 pm 22:00 11:00 pm 23:00 12:00 midnight 24:00 end of the day Converting 12-Hour to 24-Hour Format A 24-hour clock, sometimes referred to as military time, states the time according to the number of hours that have passed since midnight.
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