Free online stopwatch
Use this stopwatch to measure elapsed time for workouts, laps, presentations, and experiments. For timed countdowns with alarms and multiple simultaneous timers, use our separate Countdown Timer tool.
Stopwatch features
Precision timing
Timing uses performance.now() with a display that updates every 10 ms. You see hours, minutes, seconds, and hundredths — enough for most training and lab-style timing.
Lap timing
Press Lap while running to store each split and the cumulative time. With more than one lap, the fastest split is highlighted in green and the slowest in red. Copy Laps exports the list as plain text.
Common uses for a stopwatch
| Use case | What to measure | Laps useful? |
|---|---|---|
| Running / Cycling | Total time, pace per km/mile | Yes — lap each km/mile |
| Swimming | Length times, set times | Yes — lap each length |
| Interval training | Work and rest periods | Yes — lap each interval |
| Cooking | Cooking durations | Countdown Timer |
| Presentations | Talk duration, section timing | Yes — lap each section |
| Classroom activities | Task completion time | No |
| Science experiments | Reaction times, durations | Yes |
| Board game turns | Per-player time limits | Yes — lap each turn |
Stopwatch vs countdown — quick pick
| Scenario | Best tool | Reason |
|---|---|---|
| You need to know how long something took | Stopwatch (this page) | Counts up from zero |
| You need to be alerted when time is up | Countdown Timer | Alarm at zero — see countdown tool |
| You need to compare interval splits | Stopwatch with laps | Lap comparison feature |
| You have a fixed time budget for a task | Countdown Timer | Visual countdown and alarm |
Tips
- Keyboard: Space starts and pauses; L records a lap while running; R resets when stopped.
- Need an alarm at zero? Switch to the Countdown Timer for presets, progress bar, and Web Audio alerts.
Frequently asked questions
How accurate is this online stopwatch?
Online stopwatches using performance.now() are typically accurate within a few milliseconds for practical use. For best results, keep this tab visible while timing; background tabs may update the display less often.
How do I time a presentation with this stopwatch?
Start when you begin speaking and tap Lap at each section break. Afterward, compare splits to see which parts ran long.
Does the stopwatch continue when I switch tabs?
Yes. Elapsed time keeps accruing. Only the refresh rate of the on-screen digits may slow down in a background tab; underlying time is still based on the system clock.
Is this stopwatch free?
Yes. No account and no download.