Time calculator

This time calculator handles everyday time arithmetic. The first tab finds the duration between two clock times — perfect for working out shift lengths, study time, or how long a task took. The second tab adds or subtracts hours, minutes, and seconds from a starting time and tells you if the result rolls over to the next or previous day.

How it handles overnight times

If the end time is earlier than the start time, the duration tool assumes the end is on the following day — useful for night shifts that cross midnight. When adding or subtracting, the calculator shows how many days the result shifts so the time of day is always correct.

Related tools

For whole-date arithmetic, use the date calculator; to convert between seconds, minutes, hours and days, the time unit converter; and for world times, the time zone converter.

Frequently asked questions

How many hours is 9am to 5:30pm?

8 hours and 30 minutes. Enter the two times in the “Time between” tab to confirm.