There are two primary methods of showing the time. First there's the 12 hour clock that uses AM and PM, and then there's the 24 hour clock.

Most countries prefer the 24 hour clock method, but the 12 hour clock is widely used in Latin America and English-speaking countries. In the 12 hour clock method, it is 12:00 twice a day at midnight (AM) and noon (PM).

The table below shows the conversion between the 12 hour and 24 hour clock systems:

12 hour clock 24 hour clock
12:00 AM 00:00
01:00 AM 01:00
02:00 AM 02:00
03:00 AM 03:00
04:00 AM 04:00
05:00 AM 05:00
06:00 AM 06:00
07:00 AM 07:00
08:00 AM 08:00
09:00 AM 09:00
10:00 AM 10:00
11:00 AM 11:00
12:00 PM 12:00
01:00 PM 13:00
02:00 PM 14:00
03:00 PM 15:00
04:00 PM 16:00
05:00 PM 17:00
06:00 PM 18:00
07:00 PM 19:00
08:00 PM 20:00
09:00 PM 21:00
10:00 PM 22:00
11:00 PM 23:00

12 hour clock

The day is split into two 12 hour periods running from midnight to noon (AM hours), and noon to midnight (PM hours).

The abbreviations AM and PM are from Latin:

• AM: ante meridiem, before midday
• PM: post meridiem, after midday

24 hour clock

The day runs from midnight to midnight and is divided into 24 hours from 0 (midnight) to 23. Time is shown in hours and minutes since midnight.

Converting from 12 hour to 24 hour clock

Starting from the first hour of the day (12:00 AM or midnight to 12:59 AM), subtract 12 hours:

• 12:00 AM = 0:00
• 12:15 AM = 0:15

From 1:00 AM to 12:59 PM, the hours and minutes remain the same:

• 9:00 AM = 9:00
• 12:59 PM = 12:59

For times between 1:00 PM to 11:59 PM, add 12 hours:

• 3:17 PM = 15:17
• 11:59 PM = 23:59.

Converting from 24 hour to 12 hour clock

Starting from the first hour of the day (0:00 / midnight to 0:59), add 12 hours and AM to the time:

• 0:30 = 12:30 AM
• 0:55 = 12:55 AM

From 1:00 to 11:59, simply add AM to the time:

• 2:25 = 2:25 AM
• 9:30 = 9:30 AM

For times between 13:00 to 23:59, subtract 12 hours and add PM to the time:

• 16:55 = 4:55 PM
• 21:45 = 9:45 PM