Quick answer
- Add durations only: enter one
HH:MMorHH:MM:SSvalue per line. - Subtract breaks or trims: put a leading
-in front of the line you want to remove. - Keep totals over 24 hours: this page treats every row as a duration, not a wall-clock time.
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.
- Total billable hours across tasks without forcing the result back into a 24-hour clock.
When to use this time duration calculator
This page is for duration math only. Enter one HH:MM or HH:MM:SS value per line, add or subtract rows, and keep totals as raw durations without any calendar, timezone, or daylight-saving rules.
Good fits
- Timesheets and work hours: add shifts and subtract lunch or unpaid breaks.
- Editing and production logs: total clip lengths, trim removals, or recording sessions.
- Training blocks: sum intervals, warmups, cooldowns, and rest periods.
- Long totals: keep results such as 38:45 or 100:00 without forcing a date or clock wrap.
Worked examples
Timesheet: enter 08:00, -00:30, and 07:45 on separate lines to total two shifts and subtract one unpaid break. This is the right pattern for payroll-style duration math.
Editing session: enter clip lengths such as 00:42:15, 00:18:40, and -00:03:20 to total source footage and subtract trims without introducing any date logic.
Training day: enter 00:15:00, 00:40:00, -00:05:00, and 00:10:00 to add warmup, main block, subtract a paused rest, and add cooldown in one list.
What it does not do
- No months, years, or calendar-day arithmetic.
- No timezone conversion or DST adjustment.
- No automatic wrap to 24-hour clock notation.
Why totals can exceed 24 hours or go negative
This calculator treats every line as a duration, not a wall-clock time. That is why totals like 31:15 stay above 24 hours, and why subtracting more time than you added can produce a negative result. Those behaviors are useful for raw duration math, but they are not suitable for timezone or calendar scheduling.
FAQ
What input format is supported?
Enter one duration per line in HH:MM or HH:MM:SS format. Add + or - to control each line. The parser skips blank lines.
How do I total a work shift with breaks?
Enter each paid block on its own line, then subtract unpaid breaks with a leading minus sign. For example, 08:00, -00:30, 07:45 totals two work blocks with one unpaid break removed.
Can the result be negative?
Yes. When the total is negative, the result keeps a leading minus sign in both HH:MM:SS and human-readable output.
Is there a limit to the number of hours?
No. The calculator does not wrap hours, so values such as 100:00 stay as entered.
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 reuse or share the same duration list?
Yes. Use the result URL button to copy a link that keeps the entire list, so you can send the same setup to coworkers, students, or teammates without retyping every row.
Can I add months or years?
No. Months/years are calendar units with variable lengths. Use Date Difference for those cases.
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.