Writing Style – Expressing Time

A BizWritingTip reader wanted to know whether to use numbers or words when expressing time.
BizWritingTip response: ?When you are using a.m. or p.m., use the numbers.


We will start the meeting at 8:30 a.m. (Note the space between the number and a.m.)
He can usually be found at the gym between noon and 1:30 p.m.

There is no need to add zeros for time that is “on the hour.”


We will start the meeting at 8 a.m.

When using the word o’clock, you can use either numbers or words.


The ceremony will start at two o’clock in the afternoon. (Used to indicate formality)
You must be ready by 2 o’clock. (Used for emphasis)

If the reader will easily understand whether you are discussing a morning or afternoon timeframe, you can omit the a.m. or p.m. or o’clock. You could either spell the word out for easy reading or use the figures.

Your workday ends at 4:30.
Your workday ends at four-thirty not at four twenty-eight.
Your workday ends at 16 30. (24-hour clock)