Should Minutes Be Shown with AM and PM?

Summary

To indicate exact time, show both the hour and the minute with a.m. and p.m.

Examples
  • The train leaves at 8:03 a.m. every day.
  • Submit your applications by 11:59 p.m. tonight.

For whole hours, indicating just the hour on the clock suffices.

Example
  • The train leaves at 8 p.m. every day.

Stay consistent: either show both hour and minute for all time references within a single context, or indicate just the hour.

Example
  • Poor: Class is from 2 to 3:30 p.m. on Mondays.
    Better: Class is from 2:00 to 3:30 p.m. on Mondays.

Exact time: a.m. and p.m.

Use a.m. and p.m. when indicating exact time is important. These abbreviations for time, which refer to the first and second 12-hour periods of the day, are commonly used in official, academic, and other formal communication. In everyday speech, a.m. and p.m. are not often used, since context makes it clear which part of the day is being referred to, and emphasizing exact time is generally unnecessary.

Examples
  • Formal: The submission window closes at 4:59 p.m. today.
    Informal: We need to get this done by five.
  • Formal: Your interview is scheduled for 9:30 a.m. on June 23, 2063.
    Informal: My interview is at half past nine on the 23rd.
  • Formal: We measured the length of the shadow at 3:43 p.m. and 3:55 p.m. on the day of the eclipse.
    Informal: Lulu likes to take a nap from three forty to four in the afternoon (or 3:40 to 4 o’clock in the afternoon).
Tip

Use numerals to indicate time with a.m. and p.m.

Example
  • Incorrect: We leave at nine a.m. tomorrow
    Correct: We leave at 9 a.m. tomorrow.

Hours and minutes

Since a.m. and p.m. emphasize exact time, both hours and minutes are usually mentioned. However, for whole hours, indicating just the hour is generally sufficient, unless required by context. In other words, you may omit the zeroes for minutes with whole hours.

Examples
  • I’ll be done by around 8 p.m. (or 8:00 p.m.).
  • This report is due at 9:30 a.m. tomorrow.
  • Your flight will take off at 8:25 a.m., as scheduled.
  • The movie starts at 6 p.m. (or 6:00 p.m.).
Tip

Don’t use expressions like in the afternoon with a.m. and p.m., which already make it clear which part of the day is being referred to.

Examples
  • Poor: Tea is served at 4 p.m. in the afternoon.
    Better: Tea is served at 4 p.m.
    Better: Tea is served at four in the afternoon.
  • Poor: Class starts at 9 a.m. in the morning.
    Better: Class starts at 9 a.m.
    Better: Class starts at nine in the morning.

Consistency

Either indicate just the hour or show both hour and minute consistently for all time references within a single context. Also make sure to include a.m. or p.m. in all references where omitting the abbreviation could cause confusion. Consistency improves clarity and makes text easier to scan and understand.

Examples
  • Poor: Class is from 11 a.m. to 4:30 p.m.
    Better: Class is from 11:00 a.m. to 4:30 p.m.
  • Poor: We worked from 4 to 8:00 p.m.
    Better: We worked from 4:00 to 8:00 p.m.
    Better: We worked from 4 to 8 p.m.
  • Poor: The eclipse lasted from 9:13 to 3:07 p.m.
    9:13 a.m. or p.m.?
    Better: The eclipse lasted from 9:13 a.m. to 3:07 p.m.
Tip

If an abbreviation like a.m. or p.m. appears at the end of a sentence, don’t add another period after it.

Example
  • Incorrect: I will be in a meeting from 11:30 a.m. to 12:30 p.m..
    Correct: I will be in a meeting from 11:30 a.m. to 12:30 p.m.

Quick Quiz

Which is correct?
Choose from these answers
All done!
Which is better style?
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All done!

Did You Know?

An acronym is an abbreviation pronounced as a single word (e.g., NASA, NATO).
Know more:Acronym or Initialism? Types of Abbreviations