How to use it
Press Start to begin and Start again to pause — the elapsed time holds until you reset. Lap records a split without stopping the clock, so you can time a series of intervals and compare them afterwards. The spacebar starts and stops and L records a lap, which means you can run the whole thing without looking away from what you are timing.
Laps and splits
Each lap shows both the split — the time since the previous lap — and the cumulative total. That distinction matters when timing repeated efforts: the split tells you how fast that interval was, the total tells you where you are in the session. Laps stay on screen until you reset, and you can copy them all at once.
How accurate is a browser stopwatch?
Timing is taken from the system clock at the moment you press the button, so precision is limited by how quickly the browser registers your input rather than by the clock itself — realistically within a few hundredths of a second. That is more than adequate for training intervals, cooking, presentations and classroom activities. It is not adequate for officiating a race where hundredths decide the result; that needs hardware timing.