Online stopwatch
Start, stop, reset, and record lap and cumulative times in the browser.
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How to use it
Press Start, then Lap to record splits. Space starts and stops. Reset clears everything.
Good to know
Timing uses your device clock. Elapsed time is calculated from timestamps. Background suspension, device sleep, or a discarded tab can affect updates and continuity.
Record a timed sequence
Press Start, then Lap at each checkpoint. A lap entry shows the time since the previous lap and the total elapsed time. Press Stop to pause, Start to continue, and Reset to clear the displayed time and all laps. When a non-form control has focus, Space also starts or stops the watch.
The display is calculated from performance.now() while running, so a slower screen redraw does not turn every missed animation frame into lost elapsed time.
Use a dedicated timer for critical timing
Browser scheduling can slow visual updates in background tabs, and page navigation or reload clears the watch. This stopwatch has no export, persistence, or synchronization. It is suitable for informal elapsed time and lap notes, not for officiating, laboratory work, or any measurement needing traceable accuracy.
Frequently asked questions
Does the stopwatch keep running in another tab?
Elapsed time uses timestamps rather than counting screen refreshes. A suspended or discarded page and device sleep can still affect behavior; this is not a precision timing instrument.
Can I record lap times?
Yes. Press Lap to record the split and lap time.
Is there a keyboard shortcut?
Space starts and stops the stopwatch.