Online Stopwatch
Start, stop and record laps with your keyboard — space to start or stop, L to lap.
This online stopwatch counts up from zero with hundredth-of-a-second precision and records unlimited laps. It is built for speed of use: tap the space bar to start or stop, press L to mark a lap, and R to reset. No hunting for buttons while the athlete crosses the line.
Each lap is listed with its split time and the total elapsed time, so you can see both how long each interval took and where you are overall — exactly how a physical sports stopwatch behaves, minus the tiny buttons.
It runs entirely in your browser tab and is free with no account. Because it lives in the tab, closing the tab ends the session, so keep it open while you are timing.
How to use the stopwatch
- Press Start — or just hit the space bar.
- Press L (or the Lap button) each time you want to record a split.
- Hit space again to stop the clock.
- Review the lap list: split time and cumulative time for each lap.
- Press R or Reset to clear everything and start fresh.
Laps vs splits, quickly explained
A lap time is how long one interval took (lap 2 alone: 1:42.50); a split is the total time on the clock at that moment (after lap 2: 3:29.80). This stopwatch shows both per row, so runners can check pacing lap by lap while still tracking overall race time.
Typical uses: interval training on the track, timing swim sets, science experiments, speedcubing practice, timing a presentation run-through, or settling how long the kettle actually takes. For counting down instead of up, switch to the timer tool.
How the stopwatch keeps time
Rather than counting ticks in a loop — which drifts whenever the browser is busy — this stopwatch records the exact moment you press Start and measures elapsed time against your device's high-resolution clock. Each lap stores its own timestamp, so the numbers stay honest even if the page briefly stutters.
It all runs locally in the tab, with no account and nothing uploaded. Switching to another tab does not corrupt the count; come back and the elapsed time is exactly right. Closing the tab, however, ends the session, because there is no server keeping it alive in the background.
Built for keyboard-first timing
When you are timing a runner across a line, hunting for a button costs you tenths of a second. The shortcuts remove that: the space bar starts and stops, L records a lap while running, and R resets. Your eyes stay on the event, not the screen.
The same speed helps at a desk — start a session with one keypress the instant a task begins, lap each phase, and stop without reaching for the mouse. On phones and tablets, on-screen Start, Lap and Reset buttons take over and are sized for thumbs.
What people time with the stopwatch
On the track and in the pool it times intervals, repeats and rest, and coaches lap each rep to spot an athlete fading. In the lab it times reactions and observations, and speedcubers and gamers use it to shave hundredths off a personal best.
Away from sport it is just as handy: timing a speech or presentation run-through, seeing how long a chore actually takes, timing a phone call, or settling the household debate about how long the kettle really needs. Anything you want to measure rather than count down, the stopwatch handles.
Reading the lap table
Every lap row shows two numbers: the lap time (how long that single interval took) and the cumulative split (the total on the clock at that point). Together they let you read pacing and overall progress at a glance without any mental subtraction.
Because there is no cap on laps, you can record a split for every rep of a long session and scroll the list afterwards to find the slow one. Reset clears the whole table when you are ready for a fresh session.
How accurate is it, really?
The display shows hundredths of a second and draws on the browser's high-resolution timer, which is far more precise than any human-scale timing needs. In practice the largest error is not the tool at all — it is your reaction time on the space bar, usually a tenth to two-tenths of a second.
For fairness, start and stop the same way each time so that reaction delay stays consistent across laps. If you need certified results for an official event, dedicated hardware with electronic triggers is the right tool; for training, coaching and everyday use, this is accurate and dependable.
Related tools
If you want to count down from a set time and be alerted at zero rather than count up, use the timer — it is the mirror image of the stopwatch, with quick presets and a sound alert.
For focused work sessions with automatic breaks, the Pomodoro timer handles the work-and-rest rhythm, and for counting the days to a future date the countdown-to-date tool keeps a live tally that survives closing the page.
Frequently asked questions
What are the keyboard shortcuts?
Space starts and stops the clock, L records a lap while running, and R resets. Shortcuts work whenever the stopwatch tab is focused, which is much faster than clicking.
Is the stopwatch accurate?
It displays hundredths of a second and uses your browser's high-resolution clock, which is accurate for human-scale timing. The real error in most timing is reaction time on the space bar, roughly 0.1 to 0.2 seconds.
How many laps can I record?
There is no fixed limit. Record as many as your session needs; each shows its own lap time and the cumulative total.
Does it keep running if I switch tabs?
Yes. Elapsed time is tracked against the clock, not by counting ticks, so returning from another tab shows the correct time. Closing the tab, however, ends the stopwatch — it runs in your browser only.
Is it free?
Yes. Free, unlimited, no sign-up, and nothing you time is sent anywhere — the whole stopwatch runs locally.
Does it work on phones and tablets?
Yes. On touch devices the on-screen Start, Lap and Reset buttons replace the keyboard shortcuts, and they are sized for thumbs.