How to Convert 24-Hour Time to 12-Hour Time (Chart and Examples)

Your boarding pass says the flight leaves at 18:40. A shift roster lists a meeting at 21:15. If you are used to AM and PM, these numbers take a second to decode.

This guide shows you how to convert 24-hour time to 12-hour time with one simple rule, plus a full conversion chart and worked examples.

What is 24-hour time?

The 24-hour clock counts the hours of the day straight through from 00 to 23. The day begins at 00:00 and ends at 23:59.

Because every hour has its own number that never repeats, there is no need for AM or PM and no room for confusion.

The 12-hour clock splits the day into two halves instead, and always needs AM or PM to say which half you mean.

So converting from 24-hour to 12-hour time does not change the moment itself. It only changes how you write it.

How to convert 24-hour time to 12-hour time

Look at the hour on its own, then apply whichever of these four cases fits:

Case 1: hours 01 to 11

Keep the number and add AM.

09:20 → 9:20 AM

Case 2: hours 13 to 23

Subtract 12 from the hour and add PM.

18:40 → 18 − 12 = 6 → 6:40 PM

Case 3: hour 12

It stays 12 and it is noon.

12:30 → 12:30 PM

Case 4: hour 00

It becomes 12 and it is just after midnight.

00:45 → 12:45 AM

In short: anything above 12 loses 12 and becomes PM; anything below stays as it is and becomes AM.

24-hour to 12-hour conversion chart

Worked examples

Example 1: a flight at 18:40

The hour is above 12, so subtract 12:

18 − 12 = 6

Result: 6:40 PM

Example 2: a meeting at 21:15

21 − 12 = 9

Result: 9:15 PM

Example 3: a shift starting at 08:00

The hour is below 12, so it stays as it is:

Result: 8:00 AM

Example 4: a 00:30 timestamp

Hour 00 becomes 12 AM:

Result: 12:30 AM

Example 5: the last minute of the day, 23:59

23 − 12 = 11

Result: 11:59 PM

Common mistakes to avoid

Turning 00:30 into 12:30 PM. It is 12:30 AM, just after midnight, not just after noon.

Subtracting 12 from hour 12. 12:00 stays 12:00 PM. It does not become 0.

Leaving out AM or PM. On a 12-hour clock the time is incomplete without it, since 7:00 alone says nothing.

Changing the minutes. Minutes always stay the same. Only the hour is converted.

When do you need this conversion?

Reading airline tickets, which print departure and arrival times in 24-hour form.

Setting alarms and calendar events when your phone uses a different format than the schedule you were given.

Working with rosters and shift patterns in hospitals, factories, and logistics.

Reading system logs, since software records timestamps on a 24-hour clock.

Frequently asked questions

What time is 13:00?

It is 1:00 PM.

What time is 15:00?

It is 3:00 PM.

What time is 17:00?

It is 5:00 PM.

What time is 18:00?

It is 6:00 PM.

What time is 20:00?

It is 8:00 PM.

What time is 22:00?

It is 10:00 PM.

What time is 00:00?

It is 12:00 AM, midnight, the start of the new day.

What is the difference between 12:00 and 00:00?

12:00 is noon and 00:00 is midnight. They are twelve hours apart.

Summary

Converting 24-hour time to 12-hour time comes down to a single rule:

If the hour is above 12, subtract 12 and write PM. If it is below 12, keep it and write AM.

With two exceptions: 00 becomes 12 AM, and 12 stays 12 PM.

And if you would rather get the answer without doing the arithmetic yourself, use the online calculators at OurDailyTools to convert between the two formats in seconds.