12-Hour and 24-Hour Time
Compare 12- and 24-hour time systems and solve practical problems involving the conversion between them.
Read this first
After midday, add 12 to get 24-hour time. Before midday, the numbers match.
The day runs from 00:00 to 24:00.
Words you need
- am
- Before midday.
- pm
- After midday.
- 24-hour time
- Time written with four digits, like 15:30.
Worked example
e.g. Write 3:45 pm in 24-hour time.
- It is pm, so it is after midday.
- Add 12 to the hours. 3 + 12 = 15.
- The minutes do not change.
- 3:45 pm is 15:45.
Always write four digits. 9 am is 09:00.
Practice
The pictures fade as you go. By the last few you are on your own.
1Write 7:00 am in 24-hour time.with a picture
Answer07:00.
2Write 8:30 pm in 24-hour time.with a picture
Answer20:30.
3Write 18:15 in 12-hour time.with a hint
Need a hint?
Take away 12 from the hours.
Answer6:15 pm.
4Write 00:30 in 12-hour time.with a hint
Need a hint?
That is just after midnight.
Answer12:30 am.
5Write 11:20 am in 24-hour time.on your own
Answer11:20.
6Write 23:45 in 12-hour time.on your own
Answer11:45 pm.
7A train leaves at 14:10. Is that morning or afternoon?on your own
AnswerAfternoon. It is 2:10 pm.
Think about it
1
Why does the world use 24-hour time?
One good answerThere is no confusion between morning and evening.
2
What is 12:00 pm in 24-hour time?
One good answer12:00. Midday does not change.
Common mistakes
Adding 12 to am times.
Only pm times get 12 added.
Writing 5:30 pm as 5:30.
It must be 17:30, with four digits.