How precise is the stopwatch?

Timing is measured with Date.now() deltas, which gives millisecond accuracy. The display updates at your screen refresh rate (typically 60 frames per second) and shows milliseconds directly.

Will the stopwatch drift if I leave the tab running in the background?

No. Elapsed time is calculated from the start timestamp plus any accumulated offset, not by counting ticks, so browser background-tab throttling has no effect on accuracy.

Can I keep my laps when I pause and resume?

Yes. Pause and resume preserve all recorded laps. Laps are only cleared when you press Reset.

Stopwatch

Precise stopwatch with millisecond accuracy and lap tracking.

00:00:00.000

Countdown Timer

Set a timer for any duration. Get an alert when time is up.

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Convert times between any IANA timezones with DST awareness.

Pomodoro Timer

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Convert Unix epoch timestamps to dates and back, in seconds or milliseconds.

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Calculate exact age in years, months, days, hours, and seconds.

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Add or subtract from a date, or measure the duration between two dates.

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Run work/rest intervals for HIIT, Tabata, and circuit workouts.

Alarm Clock

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