Timers / 03
Online Stopwatch
Time anything to the hundredth of a second, record laps, see the fastest and slowest lap, and copy or download the results as a CSV file.
Online Stopwatch: The stopwatch remembers when it started and adds up the time between starts and stops, so it keeps counting in a background tab and after a reload. Laps show each split and the running total, and the fastest and slowest are marked once there are three. Runs 100% locally in your browser with zero server file uploads.
- Category
- Time & calendar tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Space starts and stops, L records a lap, R resets. The stopwatch keeps running if you reload or close the tab, because it only remembers when it started.
What limits a stopwatch's accuracy
The stopwatch reads the computer's clock, which is accurate to a few milliseconds, and the display updates with the screen, usually 60 times a second. The weak point is the person pressing the button: a simple reaction takes around a fifth of a second, and it varies by several hundredths between presses.
That error applies at both ends, so it mostly cancels when the same person starts and stops the watch in the same way. For races and sports records, where hundredths matter, electronic timing with sensors or photo finish is used for exactly this reason.
Laps and splits
Pressing Lap records the running total at that moment. The table shows each lap's own time, the difference between one total and the previous, and the total itself; with three laps or more, the fastest is marked in green and the slowest in red.
Copy the laps to paste them into a spreadsheet, or download them as CSV. The stopwatch stores only the moment it started, so it keeps counting after a reload. For timed work and rest, the interval timer runs a whole plan.
How to use it
- Press Start, or the Space key.
- Press Lap, or L, at each split.
- Stop, then copy the laps or download them as CSV; R resets.
Privacy & limitations
Everything runs in your browser. The running time and laps are kept in this browser only.
Related tools
Frequently asked questions
How accurate is it?
It reads the computer's clock, which is accurate to a few milliseconds, and the display updates with the screen, usually 60 times a second. Your reaction time when pressing the button is by far the biggest error, typically around a fifth of a second.
Does it keep running if I close the tab?
Yes. It stores the moment it started, so when you open the page again it shows the time that has passed. It does not need the tab to stay open, unlike the timers that have to ring.
Are there keyboard shortcuts?
Space starts and stops, L records a lap while it runs, and R resets once it is stopped. They are ignored while you type in a field.
Can I export the laps?
Copy them as a tab-separated table that pastes into a spreadsheet, or download a CSV file with the lap number, lap time, and total time.
Free tool · runs in your browser · no account required