Stopwatch — Online with Lap Times
Free online stopwatch with start, stop, lap and reset. Accurate to milliseconds.
How to use this tool
- Open this page — it runs instantly in your browser, no signup or install.
- Allow any permission prompt if asked; everything stays on your device.
- Use the on-screen controls — results update live.
Free online stopwatch with start, stop, lap and reset. Accurate to milliseconds.
How it works
This online stopwatch measures elapsed time with millisecond precision directly in your browser. Press Start to begin, Stop (or Pause) to freeze the display, and Reset to clear it back to zero. The Lap button records a split time without stopping the main clock, letting you compare intervals.
All recorded lap times are displayed in a list below the main timer, each showing both the split duration (time since the last lap) and the cumulative elapsed time. You can copy or note these values for record-keeping after your session.
Because this runs in a browser tab, it is suited for activities where you have a screen in front of you: timing presentations, cooking steps, coding sprints, workout intervals, or races where a phone stopwatch would suffice. For scientific measurement requiring sub-millisecond accuracy, use a dedicated hardware timer.
The stopwatch continues running if you switch to another browser tab, but closing the tab or refreshing the page will reset it. If you need to preserve lap records, copy the lap list to a text file before closing.
Worked example
Time a series of workout intervals
- Press Start at the beginning of the first interval.
- Press Lap when the first interval ends — the lap time is recorded.
- Continue; press Lap at the end of each subsequent interval.
- Press Stop at the end of the session.
- Review the lap list to compare each interval duration.
A complete split-time record of every interval without stopping the overall timer.
Common mistakes to avoid
- Pressing Reset instead of Lap and losing all previously recorded splits.
- Closing the browser tab mid-session and losing the lap record — copy data before closing.
- Expecting the stopwatch to alert you at a specific time; it only measures elapsed time, not countdowns.
Key terms
- Lap time
- The elapsed time between two consecutive Lap presses, representing a single split or interval.
- Cumulative time
- The total elapsed time from Start up to the moment the Lap button was pressed.
- Millisecond
- One thousandth of a second (0.001 s). The stopwatch displays to this resolution for precise short-duration timing.
Frequently asked questions
- How accurate is the stopwatch?
- It uses requestAnimationFrame and Date.now(), giving millisecond precision in modern browsers.
- Can I record lap times?
- Yes — press Lap while the stopwatch is running to record split times.