Morning times (am)
From 1:00 am to 11:59 am, the 24-hour time has the same hour and the same minutes. A single-digit hour gets a zero in front.
| 12-hour | 24-hour |
|---|---|
| 8:15 am | 08:15 |
| 11:40 am | 11:40 |
24-hour time never uses am or pm.
Year 3
Tell and write the time from 12-hour and 24-hour clocks
Match times between 12-hour wording and 24-hour notation, including noon and midnight.
Lesson overview
Time
A 12-hour clock uses am and pm. Am is for times after midnight and before noon, in the morning. Pm is for times after noon and before midnight, in the afternoon and evening. Noon is 12 o'clock in the middle of the day. Midnight is 12 o'clock at night, when one day ends and the next day begins. A 24-hour clock counts the hours from 00:00 to 23:59 and does not use am or pm.
Noon and afternoon times (pm)
Noon is 12:00 pm, and it is written 12:00 in 24-hour time. Just after noon the hour is still 12, so 12:30 pm is 12:30. From 1:00 pm to 11:59 pm, add 12 to the hour.
| 12-hour | 24-hour |
|---|---|
| 12:00 pm (noon) | 12:00 |
| 12:30 pm | 12:30 |
| 3:15 pm | 15:15 |
| 11:45 pm | 23:45 |
12:30 pm, just after noon
Add 12 only from 1:00 pm onwards. Do not add 12 to 12 pm.
Midnight and just after (12 am)
Midnight is where one day ends and the next day begins. The new day starts at 00:00 in 24-hour time, and 12:00 am is the same time. Times just after midnight, such as 12:20 am, are 00:20.
| 12-hour | 24-hour |
|---|---|
| 12:00 am (midnight) | 00:00 |
| 12:20 am | 00:20 |
| 1:30 am | 01:30 |
In 12:xx am, the 12 becomes 00. From 1:00 am the hour stays the same.
Worked example
Write 12:40 pm and 6:40 pm in 24-hour time.
| 12-hour | 24-hour |
|---|---|
| 12:40 pm | 12:40 |
| 6:40 pm | 18:40 |
- Both times are pm. Ask: is the hour 12?
- 12:40 pm is just after noon, so the hour stays 12. The 24-hour time is 12:40.
- 6:40 pm is after 1:00 pm, so add 12 to the hour: 6 + 12 = 18.
- The minutes stay the same, so 6:40 pm is 18:40.
Try it
Decide whether the time is am or pm. Then check whether the hour is 12. The minutes never change.
Question 1
What is 3:20 pm in 24-hour time?
Question 2
What is 07:45 in 12-hour time?
Question 3
Write the 24-hour hour number for 8:10 pm.
Question 4
What is 12:30 pm in 24-hour time?
Question 5
What is 00:20 in 12-hour time?
Common mistakes
Watch for these when working through the lesson.
- Forgetting to add 12 for afternoon and evening times.
- Adding 12 to 12 pm, such as writing 12:30 pm as 24:30.
- Keeping 12:20 am as 12:20 instead of writing 00:20.
- Using am and pm with a 24-hour time.
- Changing the minutes when only the hour form should change.
Related topics
These ideas fit closely with this lesson.
- Tell and write the time from an analogue clock, including using Roman numerals from I to XII.
- Estimate and read time with increasing accuracy to the nearest minute.