Free Online Stopwatch
Start, stop, and reset a precise stopwatch and record lap times to the centisecond. It runs entirely in your browser with no install or sign-up.
00:00.00
MM:SS.cs (minutes : seconds . centiseconds)
Press Start, then Lap to record split times. Nothing is recorded until you start.
Quick answer
A stopwatch counts time upward from zero. Press Start to begin, Stop to pause, and Reset to clear it. The Lap button records the current time and the split since the previous lap, so you can compare segments. This stopwatch is accurate to a hundredth of a second and runs entirely in your browser.
Formula & method
The stopwatch measures elapsed time using the browser's high-resolution performance clock rather than the wall clock, so it is not affected by the system time changing. While running it updates about 30 times a second and displays minutes, seconds, and centiseconds. Each Lap stores the current elapsed time and shows the split (the time since the previous lap).
Examples
- Input
- Start → work → Stop
- Result
- Elapsed shown as MM:SS.cs
- Why
- Measure how long something takes, like a chore or a code build, to the hundredth of a second.
- Input
- Start → Lap → Lap
- Result
- Each lap with its split time
- Why
- Record several laps to compare segment times, useful for running intervals or repeated trials.
- Input
- Start → Stop → Start
- Result
- Continues from the paused time
- Why
- Stopping pauses the count; starting again resumes from where you left off instead of restarting.
When to use this tool
- Timing workouts, runs, or interval splits with lap records.
- Measuring how long a task, experiment, or process takes.
- Timing games, presentations, or speed challenges.
Common mistakes
- Pressing Reset instead of Stop — Reset clears everything, while Stop simply pauses so you can resume.
- Expecting the stopwatch to run after the tab is closed; it only counts while the page is open.
- Confusing the lap split with the total time — the split is the time since the last lap, not the running total.
Frequently asked questions
How accurate is the online stopwatch?
It uses the browser's high-resolution performance clock and displays centiseconds (hundredths of a second). It is accurate enough for everyday timing, though it is not a certified instrument for official competition results.
What does the Lap button do?
It records the current elapsed time and the split since the previous lap, building a list you can review. The main stopwatch keeps running while you record laps.
Can I resume after stopping?
Yes. Stop pauses the count and Start resumes it from the same value. Use Reset only when you want to clear the time and laps and start over.
Does it keep timing if my screen sleeps?
It keeps timing while the page is open, but the display updates only when the tab is active. Backgrounded or sleeping devices may pause visual updates until you return.
Is my data saved anywhere?
No. Everything runs in your browser and nothing is uploaded. Your times and laps are cleared when you reset or close the page.
What is the difference between a stopwatch and a timer?
A stopwatch counts up from zero to measure elapsed time, while a countdown timer counts down from a set duration to zero and alarms. Use the Countdown Timer for the latter.
Sources & references
External references open in a new tab. We are independent and not affiliated with these organizations.
- ✓ Free to use
- ✓ No sign-up required
- ✓ Runs entirely in your browser — nothing is uploaded.
- ✓ Formula and method shown above
Provided “as is” for general information only — results may be inaccurate, so verify before you rely on them. No warranty; use at your own risk.
Built and reviewed by HIFreeTools against the formula shown above and any authoritative references cited on this page. See our methodology and editorial standards.
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