Stopwatch and timer
A stopwatch with laps and a countdown timer, in one page that opens instantly. No advertising, no sign-in, and it keeps counting correctly while the tab is in the background. Space starts and stops it, L takes a lap, R resets.
00:00.00
Space to start and stop · L for a lap · R to reset
Laps0
No laps yet — press Lap while it runs.
Why a browser stopwatch usually drifts
Most web stopwatches add a fixed amount to a running total every time a timer fires — sixteen milliseconds, say, sixty times a second. That works until the browser is busy, and it fails completely when you switch tabs: a background tab has its timers throttled to once a second or less, so the count quietly loses minutes while you are not looking.
This one records the instant you pressed start and, on every frame, subtracts. There is nothing to accumulate and therefore nothing to lose. It also reads the monotonic clock rather than the wall clock, so if your machine syncs its time or crosses a daylight-saving change mid-run, the reading is unaffected.
The hundredths are shown in a lighter weight on purpose. At full weight the last two digits flicker so fast that the whole number becomes unreadable while it runs, which is a strange thing for a clock to do.
How to use this
- Space starts and stops it. L records a lap while it runs, R resets.
- Switch to Timer for a countdown: pick a preset or type any number of minutes.
- Lap times show the split — the length of that leg — next to the running total.
Worth knowing: Timing precision is limited by your reaction on the button, about a tenth of a second, not by the clock. For anything that needs to be defensible, use equipment that starts itself.
FAQ
Does it keep running if I switch tabs?
Yes. Elapsed time is measured from the moment you pressed start rather than counted up tick by tick, so a browser throttling the page in the background cannot make it drift. Come back after an hour and the reading is exactly right.
Can I use the keyboard?
Space starts and stops, L records a lap while it runs, and R resets. Every control is also a real button, so it works by touch and with a screen reader.
What is the difference between split and total?
The total is the time from the start to that lap. The split is the time since the previous lap — the length of that leg on its own. Both are shown, because which one you want depends on what you are timing.
How accurate is it?
It reads the browser's monotonic clock, which is not affected by the system clock changing, and displays hundredths. That is far finer than human reaction time on the button, which is the real limit at about a tenth of a second.