Why Use This Millisecond Stopwatch?
People reach for this tool for physics and chemistry experiments, speedcubing and speedrun timing, and reaction-time drills. It loads instantly, works on phones, tablets, and computers, and needs no account or installation.
Everything runs locally in your browser — there is no server to trust with your data and nothing to configure. Open the page and the tool is ready.
Laps and Precision
Press Lap while the stopwatch is running to record a split without stopping the clock. Laps are listed below the display with the total elapsed time at each point.
The stopwatch is driven by a high-resolution timestamp loop instead of a simple interval, so it stays accurate even if your device throttles background tabs.