12-Hour and 24-Hour Time
Year 5 · Maths · Free — no account needed
12-Hour and 24-Hour Time
12-hour time
12-hour time uses the numbers 1 to 12, with am (before midday) or pm (after midday) to say which half of the day it is. Midnight is 12:00 am and midday (noon) is 12:00 pm.
24-hour time
24-hour time counts hours from 0 to 23, starting at midnight (00:00) and running all the way through to just before the next midnight (23:59). There's no am or pm needed — the number itself tells you the time of day.
Converting am/pm times to 24-hour time
- 12:00 am (midnight) = 00:00
- 1:00 am to 11:59 am = same hour number in 24-hour time (e.g. 9:15 am = 09:15)
- 12:00 pm (midday) = 12:00
- 1:00 pm to 11:59 pm = add 12 to the hour (e.g. 3:00 pm = 15:00, because 3 + 12 = 15)
Converting 24-hour time to 12-hour time
- 00:00 = 12:00 am (midnight)
- 01:00 to 11:59 = same hour number, am (e.g. 07:30 = 7:30 am)
- 12:00 to 12:59 = 12:00 pm to 12:59 pm (midday hour)
- 13:00 to 23:59 = subtract 12, pm (e.g. 19:45 = 7:45 pm, because 19 − 12 = 7)
Worked Example
Convert 4:30 pm to 24-hour time. Step 1: 4:30 pm is after midday, so we add 12 to the hour. Step 2: 4 + 12 = 16. Step 3: Keep the minutes the same: 30. 4:30 pm = 16:30
Practice
Convert 9:00 am to 24-hour time.
Flashcards
What does 'am' mean?
Before midday (ante meridiem) — midnight through to just before noon.
What does 'pm' mean?
After midday (post meridiem) — noon through to just before midnight.
What is midnight in 24-hour time?
00:00
What is midday (noon) in 24-hour time?
12:00
How do you convert a pm time (1 pm–11 pm) to 24-hour time?
Add 12 to the hour. E.g. 5 pm → 5 + 12 = 17:00.
How do you convert an am time (1 am–11 am) to 24-hour time?
Keep the hour the same. E.g. 8 am → 08:00.
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