How to Distinguish Between AM and PM

As the AM and PM clock is not widely used around the world, some people may not fully understand what it stands for, and how you can tell the time with it. 5-Minute Crafts prepared a guide to explain to you how it works.

1. The difference between AM and PM

AM is the exact opposite of PM. For one, AM means “Ante Meridiem” or “before midday” (morning), and PM means “Post Meridiem” or “after midday” (afternoon and evening). Since this clock centers itself around midday, it goes like this:

• AM ranges from 00:00 to 11:59.
• Reset.
• PM ranges from 12:00 to 11:59.
  

2. Where it’s used

It’s common to English-speaking states and territories that were once part of the British Empire (UK, US, Canada, Australia, New Zealand, Mexico, Egypt, Malta, Malaysia, and the Philippines).

Note: You could argue that the 12H clock (AM and PM) is easier to pronounce. For example, it’s easier to say 6 PM instead of 18 hours.

3. The 24H clock

Unlike the AM and PM clock time, the 24H one is the most commonly used in digital clocks. It uses numbers ranging from 00:00 to 23:59 to tell the time. It doesn’t require the use of AM and PM to differentiate between morning and afternoon, either. This is because the afternoon starts when its numbers become bigger than 12. For example, on the 12H (AM and PM) clock, 5:30 PM would be right, and on the 24H one, 17:30 PM would be wrong.

4. Converting from an AM and PM clock to a 24H clock

To convert any time from standard time (AM and PM) to the 24-hour clock, subtract 12 hours from the first hour of the day (midnight). For example, considering a day has 24 hours, 12 AM turns into 0:00H, 3 PM into 15:00H, and 10:00 AM would turn into 10:00H.

Note: From 1 PM to 11:59 PM, add 12 hours. Example: 3 PM + 12 = 15H.

5. Converting from a 24H clock, to an AM and PM clock

Here, add 12 hours instead, starting from the first hour of the day (midnight). For example, 0:14H would turn into 12:40 AM, 1:00H to 1 AM, and 16H into 4 PM.

Note: From 13H to 23:29H, subtract 12 hours. Example: 16H — 12 = 4 PM.