This stopwatch measures elapsed time with millisecond precision. Press Start to begin counting, Lap to record split times without stopping the main timer, and Stop to pause the count.
Formula Used
Elapsed Time = Current Timestamp − Start Timestamp + Accumulated Paused Time
Current Timestamp
— the high-resolution system clock value at the current frame
Start Timestamp
— the clock value when the stopwatch was started or resumed
Accumulated Paused Time
— time elapsed during previous start/stop cycles, added to the current run
Example Calculation
If you start the stopwatch, press Lap at 12.34 seconds, the calculator records 'Lap 1' as 12.34 seconds. The main timer continues counting uninterrupted.
Frequently Asked Questions
This stopwatch uses the browser's high-resolution system clock, accurate to a fraction of a millisecond. However, display updates are throttled to 60 frames per second for rendering performance.
A lap time is the time elapsed for a single segment of an activity. Pressing 'Lap' saves the time at that instant while the main timer continues running in the background.
Yes. Because the stopwatch calculates elapsed time by comparing absolute timestamps rather than counting ticks, it remains 100% accurate even if you switch browser tabs or lock your device.
There is no practical limit. The JavaScript timer can count up to thousands of hours before encountering any numerical limits.
Press the 'Stop' button to pause the timer, then click 'Reset' to clear the elapsed time, reset the count to zero, and clear the lap history table.