Time/Numbers
Duration Calculator
Sum or subtract several durations — handy for tallying worked hours, video length, or total task time.
An empty field counts as 0. The ± button toggles adding/subtracting the row.
Manually adding up several durations written as hours:minutes:seconds is awkward — 45 minutes + 40 minutes isn't simply "85 minutes" in normal notation. This tool adds and subtracts multiple durations at once, correctly carrying minutes into hours.
How to use it
- Add several durations in a convenient format (like 1:30:00 or 90 min) and the tool totals them instantly.
- Mark individual durations for subtraction to calculate a difference rather than just a sum.
- The result is shown in a readable format (hours:minutes:seconds) as well as a total number of seconds.
Common uses
- Totaling hours worked across several shifts or tasks in a day.
- Calculating the total runtime of a playlist of videos or podcast episodes.
- Comparing actual time spent on a task against a target (by subtracting).
Things to keep in mind
If the sum of subtractions exceeds the sum of additions, the result is shown with a minus sign — handy for seeing a shortfall of hours against a target at a glance.
Unlike the date-difference calculator, this tool works with plain durations (hours, minutes, seconds), not specific calendar dates.
Article about this tool: Duration calculator: how to correctly add up hours, minutes, and seconds
Frequently asked questions
How do I add one duration and subtract another in a single calculation?
Each row has its own ± toggle — flip it so that row is subtracted from the total instead of added. Empty fields count as 0.
Does the calculator account for months of different lengths?
No, there are no "months" or "years" fields here — only days, hours, minutes, and seconds in a fixed ratio (1 day = 24 hours). For calculations involving calendar months, use "Date Difference" instead.
What do the "decimal" total values mean?
The same total expressed as a single number with a fractional part — for example, 90 minutes is shown both as "1h 30m" and as "1.5" decimal hours, which is handy for timesheets.
Why can the sum show more than 24 hours?
That's normal and expected — unlike a wall-clock time of day, a sum of durations isn't bounded by a single day. For example, a weekly timesheet can easily total "42h 15m".
What happens if the result is negative?
If the sum of subtractions exceeds the sum of additions, the result is shown with a minus sign — useful, for instance, to see a shortfall of hours against a target.