Building number confidence: Time

4. 24-hour clock time

The 24-hour clock system uses all 24 hours in the day to accurately display the time. It is not necessary to clarify whether the time stated applies to the morning, or afternoon, as this is clear from the hour shown.

Numbers from 01 to 24 displayed in circle, with 12 at top representing noon, and 24 at bottom representing midnight


Digital clock time

Whereas an analogue clock uses pointing hands which move around the clock face to indicate the current time, a digital clock displays the exact time.

The standard display of 24-hour time on a digital clock uses four digits, two either side of a colon. The first two digits display the hour (from 00 to 23*) followed by the number of minutes (from 00 to 59) past that hour.

  • 00:00 to 12:00 are the (am) hours from midnight to midday/noon.
  • 13:00 to 23:00 are the hours from 1pm to 11pm.

*When the time reaches midnight, rather than displaying 24:00, the clock resets to 00:00, indicating the start of a new day.

A digital clock showing the time as 15:00

15:00 (3 pm)

Some digital clocks also display seconds, using an additional colon and a further two digits.

15:00:47

15:00:47 (47 seconds past 3 pm)


Stating the time

Digital (24-hour) time is spoken by stating the hour followed by the number of minutes, and the suffix ‘hrs’ (for hours) is often included.

For example:

  • 19:20 (“nineteen twenty hours”)

Time on the hour (when there are two zeros in the minutes spaces) is usually spoken with the hour followed by ‘hundred’ or ‘hundred hours’.

For example:

  • 15:00 (“fifteen hundred" or “fifteen hundred hours”)