Time Duration Calculator

Add or subtract two clock durations like 1:23:45 + 0:42:18, sum a column of times one per line, or paste any duration in any shape (1:23, 01:23:45, 5m, 2h, 90s, 1d 2h 3m) and see it normalised into every other format. All in your browser, nothing uploaded.

Duration A

Duration B

A + B A − B

Try:

Result

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Humanised—
Total seconds—
Total minutes—
A vs B—

One duration per line

Try:

Sum

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Lines parsed—
Average—
Total seconds—

Notes

Clock time, not calendar time. This tool deals in durations — pure spans of clock time with no date attached. For "5 days from now" or "how many business days between two dates", see the Date Calculator.
Accepted shapes. Hours-minutes-seconds (01:23:45), minutes-seconds (1:23), single-unit tokens (5m, 2h, 90s, 1d, 500ms), free-form mixed (1d 2h 3m 4s), and comma-separated sums (1h, 30m, 90s).
Subtraction clamps at zero. Subtracting a larger duration from a smaller one yields 0, never a negative result. Durations can't go backwards.
Bulk mode. Paste one duration per line. Blank lines are skipped; lines that don't parse are flagged with their line number and shown in the per-line table alongside the parsed values.
Everything runs in the browser. No value leaves your device.