Stopwatch
An online stopwatch that counts in hundredths, records laps into a Lap/Split/Total table, exports them as CSV, and runs from the Space and L keys.
Ready
Space starts and stops · L takes a lap — from anywhere on the page, including just after a click.
Picked up where you left it
While it runs
Holds the screen on while this is running. Your device still sleeps once you stop.
Space and L reach the clock from anywhere on the page. Turn them off if a stray key press could start, stop or lap it; the buttons still do.
Laps
Laps appear here once you record one.
How to use
- Hit Start, or press Space if your hands are busy. The count begins at 0:00.00 and repaints every frame.
- Press Lap (or L) at each split you care about. The clock never pauses for it.
- Press Space to pause. The number freezes, and pressing it again picks up from that exact hundredth instead of starting over.
- Switch to fullscreen when the digits need to be legible from the other side of a room. The shortcuts keep working there.
- Export the CSV if you want the splits, then press Reset. It empties the clock and the lap table together, and there is no undo.
About this tool
Press Start and the online stopwatch is already moving. Under an hour the readout looks like 4:07.62, which is minutes, seconds, hundredths. Cross an hour and a third field appears: 1:05:03.42. Around the digits a single second hand sweeps once a minute, so at 1:01.50 it sits a sliver past twelve; it shows where you are in the current minute, never how much is done.
Lap is the button most people came for. Press it while the clock runs and a row drops into the table underneath, carrying the lap number, that lap's own split, and the total since you started. Newest sits at the top, so lap 6 is the row your eye lands on first. Export laps (CSV) sits beside Reset from the start and wakes up with the first lap.
Space starts and stops it. L takes a lap, even straight after you click a button, and a Single-key shortcuts box under While it runs turns both keys off if a stray press is a risk. The fullscreen button scales the digits to fill the display, which is what you want when the laptop is at the far end of a gym and you are not. While the clock runs, the tab title carries the current time, so the tab strip is enough to check on it from another page.
Leaving the page doesn't kill the run. Elapsed time and the lap list are saved locally and rebuilt when you come back, and a stopwatch you left going has counted every minute you were away, because that is the thing it was measuring. Reset only wakes up once you have stopped, which is deliberate. A stray click shouldn't be able to wipe a live timing.
Timing four 400m laps
Space at the gun, then L each time the runner crosses the line. By the fourth lap the top row reads #4, 1:34.12, 6:12.48. That last lap took a minute and 34 seconds, and the whole run stands at 6:12.48.
Space again to stop, then Export laps (CSV). What downloads is stopwatch-laps.csv, a Lap,Split,Total header with lap 1 on the first row, so the file runs oldest to newest even though the table on screen runs the other way.
Good to know
- Elapsed time comes off your device's system clock rather than a monotonic timer, so if the OS quietly corrects the clock mid-run, say an NTP sync or a laptop waking up in a new time zone, the number moves with it. For workouts and kitchen timing that never comes up. For an officially timed race, use official equipment.
Frequently asked questions
How do I record a lap without stopping the clock?
Press the Lap button or tap L while it runs. A row appears with the lap number, the split since your previous lap, and the total since Start, and the count carries on through all of it. A lap pressed before any time has elapsed is ignored rather than recorded as zero.
Why can't I click Reset?
Reset stays disabled while the stopwatch is running, and also before you have timed anything at all. Stop the clock and the button comes alive. It then clears the elapsed time and every lap row at once.
What happens to my run if I reload the page?
It comes back. The current elapsed time and the lap rows are stored locally, so a refresh, a back button, or reopening the tab later rebuilds the same run. A stopwatch that was still going keeps counting through all of that.
What's inside the CSV it downloads?
Three columns and one row per lap: Lap, Split, Total. Times are written the same way the screen writes them, for example 1:34.12. The file is called stopwatch-laps.csv and opens straight into a spreadsheet with no import step.
Can I read it from the back of a room?
Fullscreen is there for exactly that. The readout is sized off the viewport width, and fullscreen drops everything else, leaving the number as the only thing on screen. Space and L still work while you are in it.
Does it show milliseconds or only hundredths?
Hundredths. The last two digits are centiseconds, so 0.01s is the finest step you will see. The timing underneath is in milliseconds, but three decimals flickering at 60 frames a second is unreadable, so the display truncates to two.
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