12-hour clock facts for kids

The 12-hour clock is a common way to tell time. It divides the 24 hours of a day into two halves. These halves are called a.m. and p.m.. The letters stand for Latin words: ante meridiem (meaning before noon) and post meridiem (meaning after noon).

A typical analog 12-hour clock

With the 12-hour clock, we count from 12, then 1, 2, all the way to 11. The time from midnight until noon is a.m. For example, 7:00 a.m. is in the morning. The time from noon until midnight is p.m. So, 7:00 p.m. is in the evening.

Most people around the world use the 12-hour clock in their daily lives. However, some groups, like the military in Canada and the US, use the 24-hour clock system.

How the 12-Hour Clock Works

The 12-hour clock uses the numbers 1 to 12. It repeats these numbers twice a day. The first 12 hours are marked with "a.m." and the next 12 hours are marked with "p.m.".

• a.m. stands for ante meridiem. This means "before midday" or "before noon". So, 1:00 a.m. is one hour after midnight. 11:00 a.m. is one hour before noon.
• p.m. stands for post meridiem. This means "after midday" or "after noon". So, 1:00 p.m. is one hour after noon. 11:00 p.m. is one hour before midnight.

Midnight is usually shown as 12:00 a.m. Noon is shown as 12:00 p.m. This can sometimes be a little confusing!

Comparing 12-Hour and 24-Hour Clocks

The table below helps you see how the 12-hour clock compares to the 24-hour clock. The 24-hour clock counts hours from 00 to 23.

Images for kids

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  Exeter Cathedral Astronomical Clock, showing the double-XII numbering scheme

See also

In Spanish: Sistema horario de 12 horas para niños