Use Cases
- Sum working hours with breaks by listing each shift and subtracting lunch.
- Keep track of podcast or video edits by adding clips and subtracting trims.
- Log endurance training intervals to see the total weekly time commitment.
FAQ
What input format is supported?
Enter one duration per line in HH:MM or HH:MM:SS format. Prefix a plus or minus sign to add or subtract the duration. Blank lines are ignored.
Can the result be negative?
Yes. If the total is negative, the calculator shows a leading minus sign for both the HH:MM:SS output and the human-readable description.
Is there a limit to the number of hours?
No. Hours are not wrapped, so values such as 100:00 are accepted and displayed as-is.
Does this account for time zones or daylight saving?
No. This calculator simply adds and subtracts durations. For zone or DST conversions, see the Time Zone Converter.
Can I add months or years?
No. Months/years are calendar units with variable lengths. Use Date Difference for those cases.
Related Calculators
How it’s calculated
- Each line is parsed as HH:MM or HH:MM:SS with an optional leading +/− sign.
- Durations are converted to seconds, summed, then normalized back to HH:MM:SS with a leading minus if negative.
- The shareable URL encodes the entire list so the same total can be reproduced exactly.