The 24-Hour Clock Explained
The 24-hour clock counts hours from 00 to 23, with no am or pm. It is standard on UK train timetables and in the armed forces.
Converting
From 01:00 to 12:59 the 12-hour and 24-hour clocks match, except that 12:00 is noon. After noon, subtract 12 to get the pm hour: 15:00 is 3 pm, 18:30 is 6:30 pm. Midnight is 00:00, and 00:30 is 12:30 am.
Where you will see it
UK railways, airlines, hospitals and the armed forces use 24-hour times. In everyday conversation most people in the UK still say 12-hour times, and write them with am or pm.
Frequently asked questions
Is 24:00 the same as 00:00?
Both mean midnight. 24:00 usually marks the end of a day, and 00:00 marks the start of the next one.