Online Stopwatch
Shortcuts: Space to start or stop, L for a lap, R to reset.
Laps
| Lap | Lap time | Total |
|---|
How to use
- Press Start, or hit the space bar, to begin timing.
- Press Lap (or L) to record a split without stopping the clock. The fastest lap is marked in green and the slowest in red.
- Press Stop to pause and Start again to resume. Reset (or R) clears the time and all laps.
How it works
The stopwatch reads the browser's high-resolution monotonic clock, performance.now(), when you press Start and again on every update. Elapsed time is the difference between those readings, added to anything saved from earlier runs.
Because the time is calculated from the clock instead of by counting screen updates, it stays correct when the tab is in the background or the browser slows down its timers.
A lap time is the elapsed time since the previous lap. The total column is the running time at the moment you pressed Lap.
FAQ
Does it keep running if I switch tabs or lock my screen?
Yes. The elapsed time comes from the system clock, not from the number of screen updates. When you come back, the display jumps straight to the correct time.
How accurate is it?
The clock is precise to well under a millisecond, but the display shows hundredths of a second. Your own reaction time when pressing a key is the biggest source of error, usually 100 to 200 ms.
What are the keyboard shortcuts?
Space starts and stops, L records a lap and R resets. The shortcuts are ignored while you are typing in a text field.
Is the time saved if I close the page?
No. Nothing is stored or sent anywhere, so closing or reloading the page clears the stopwatch. Use Copy laps first if you need to keep the numbers.