Stopwatch
Counting up instead of down
A stopwatch is the mirror image of a countdown: you don’t know the duration in advance, so instead of setting a target you just start and let elapsed time build. Press start, and the display counts up until you stop it.
The space bar starts and stops it, and L records a lap without you needing to reach for the mouse — useful when your hands are otherwise occupied.
How accurate this actually is
Elapsed time is measured against the browser’s high-resolution clock, not the wall clock, so it isn’t thrown off by anything that adjusts your system time mid-session.
The honest limit isn’t the display, it’s you: human reaction time to a visual or audible cue sits somewhere around a fifth of a second, and a hand-operated stopwatch pays that cost twice — once starting, once stopping. For anything where hundredths of a second genuinely decide the result, this is the wrong tool.
Questions people ask
What’s the difference between this and a lap timer?
This page records elapsed time only. For a running log of each individual lap alongside the cumulative total, use the split stopwatch instead.
Is a browser stopwatch accurate enough for competition?
For training and casual use, yes. For anything officially timed, no — the limiting factor is human reaction time at the button, not the clock underneath.
Does it keep counting if my laptop goes to sleep?
No. A sleeping machine stops running the page entirely, so the elapsed figure only reflects time the browser was actually awake.