Add or subtract hours, minutes, and seconds
💡 Why This Matters Adding up timesheet hours, workout splits, or video/podcast segment lengths by hand means constant carrying between seconds, minutes, and hours — easy to mess up. This tool does the carrying for you.
Hours · Minutes · Seconds
Hours · Minutes · Seconds
The 60-minute hour and 60-second minute come from the ancient Babylonians, who used a base-60 (sexagesimal) number system — it's over 4,000 years old and we still haven't switched.
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Each duration is broken into hours, minutes, and seconds, then everything is converted to total seconds for the actual math — adding or subtracting is just simple arithmetic once units match. The result is then converted back into hours, minutes, and seconds, carrying over any overflow (60 seconds rolls into 1 minute, 60 minutes rolls into 1 hour) the same way you'd do by hand, just automatically.
The result shows the combined or remaining duration in hours:minutes:seconds format, plus a decimal-hours total (useful for timesheets and payroll, where 1 hour 30 minutes needs to become 1.5). This is duration math, not clock time — there's no wraparound at 24 hours, so adding up a full week's worth of hours will correctly show totals well past 24.
Subtracting a longer duration from a shorter one produces a negative result, which isn't a meaningful duration — this calculator flags that rather than showing a confusing negative time. This tool works with durations (spans of time), not clock times or dates — for figuring out the number of days between two calendar dates, use a dedicated date calculator instead.
Use this for totaling timesheet hours across shifts, adding up workout or run splits, calculating remaining time in a project budget, or figuring out how much runtime a stack of video or podcast segments adds up to.
Add example: Duration 1 is 2h 30m 0s, Duration 2 is 1h 45m 0s. Adding: 30m + 45m = 75m = 1h 15m, carried into the hours: 2h + 1h + 1h(carried) = 4h, remaining 15m. Total: 4h 15m 0s (4.25 decimal hours).
Subtract example: Duration 1 is 5h 0m 0s, Duration 2 is 1h 45m 0s. Subtracting: 0m − 45m needs to borrow 1h (60m) from the hours, giving 4h 60m − 1h 45m = 3h 15m. Total: 3h 15m 0s (3.25 decimal hours).
Add the hours, minutes, and seconds separately, then carry over any overflow — 60 seconds becomes 1 minute, and 60 minutes becomes 1 hour. This calculator handles that carrying automatically.
The result would be negative, which isn't a meaningful duration on its own. This calculator flags that case instead of showing a confusing negative time.
Yes — this is duration math, not clock-time math, so hours can go well past 24 (useful for adding up a week's worth of work hours, for example).
The result includes a total-in-decimal-hours figure alongside the hours:minutes:seconds breakdown, so you don't have to do that conversion by hand.