Use the 12-hour clock format, with a.m. and p.m. lowercased and separated by periods. Always write time using numerals rather than words.
- Correct: 10 p.m.
- Incorrect: 10PM, 10P.M, 10 P.M, 10 pm, 10pm, 22:00, 2200, ten p.m.
If you need to use a comma after a.m. or p.m., insert the comma after the second period.
- Correct: When she said she would reach Tokyo by 10 p.m., I did not believe her.
- Incorrect: When she said she would reach Tokyo by 10 p.m, I did not believe her.
Use a colon between the hour and minutes, not a period.
- Correct: 10:30 p.m.
- Incorrect: 10.30 p.m.