Duration Calculator reads durations written as unit strings, clock strings, or plain seconds, and formats a number of seconds back into weeks, days, hours, minutes, and seconds.
It adds and subtracts durations and measures the seconds between two date-times. It runs in your browser.
Unit strings like 1h30m or 2d4h, clock strings like 1:30:00, and a plain number of seconds.
Largest units first, skipping any that are zero, in a short form like 1h 30m or a long form with words, or as a clock string.
Yes. If the second date-time is earlier, the gap is negative.
No. The tool runs entirely on this page.