A time calculator treats the inputs as durations. It can add or subtract periods longer than 24 hours without interpreting them as a time of day.
Enter a duration
Use the hours, minutes and seconds format shown by the tool. A duration of 30 hours is valid even though a clock display cycles after 24 hours.
Add or subtract
The calculator converts each duration to seconds, performs the operation and formats the result back into hours, minutes and seconds.
Avoid clock-time mistakes
For an overnight work shift, first calculate the elapsed duration. For a deadline, use a date calculator as well when the date changes at midnight.
- Keep minutes below 60 when entering standard time.
- Check whether the result can be negative.
- Include unpaid breaks separately when calculating paid hours.
Frequently asked questions
Can a duration exceed 24 hours?
Yes. Durations are not limited to one day and can be used for projects, logs or cumulative work time.
Does this calculate a time-zone difference?
No. Time-zone conversion needs the source and destination offsets as well as a reference clock time.