Online Stopwatch
Last updated: 2026-06-25
The online stopwatch is a free web tool that measures elapsed time to 0.01 seconds from the moment you press Start, and lets you record split times (lap times) with the Lap button.
It highlights the fastest and slowest laps in color, so you can compare pace at a glance for workouts, studying, cooking, and more.
Stopwatch
Lap records
Elapsed time is calculated from the difference between the start time and the current time, so the cumulative time stays accurate even in the background. The on-screen display may have an error of a few tens of milliseconds, so use it as a reference.
How to use
- Start — Press Start and time begins counting up to 0.01 seconds.
- Record laps — Press Lap while running to save the split time (lap time) and cumulative time to the list.
- Stop and reset — Use Stop to pause and resume, and Reset to clear the time and all lap records.
How to use the stopwatch and lap times
A stopwatch measures the time taken from the moment something starts until it ends. Unlike a countdown timer that counts down toward a set time, a stopwatch starts at zero and counts up. It is used widely for sports records like running or swimming, presentation practice, cooking, and measuring how long a task takes.
A lap records the time at a given moment without stopping the measurement. For example, when running four laps of a 400m track, pressing Lap each lap lets you see both the split time and cumulative time for each lap at once. This tool shows the fastest lap in green and the slowest in red, giving you an intuitive view of pace changes.
| Button | Action |
|---|---|
| Start / Stop | Starts or stops the measurement. Press again after stopping to resume. |
| Lap | Saves the current split time and cumulative time to the list while running. |
| Reset | Resets the elapsed time and all lap records to zero. |
| Copy results | Copies the recorded lap list as text to the clipboard. |
For tasks that require precise timing, it is best to also use a dedicated sports app or measuring device. If you need to be alerted after a set amount of time, use the countdown timer; to repeat focus and breaks, use the Pomodoro timer.
Frequently asked questions (FAQ)
How precise is the stopwatch?
This online stopwatch displays down to 0.01 seconds in MM:SS.cc format. If the time exceeds one hour, it automatically switches to H:MM:SS.cc format. Note that, depending on screen refresh and browser environment, the display may have an error of a few tens of milliseconds, so use it as a reference.
What is the difference between lap time and cumulative time?
The lap time is the split time from the previous lap (or the start) until you press the Lap button this time, while the cumulative time is the total elapsed time since you started. Both values appear in the list, with the fastest lap highlighted in green and the slowest in red.
Is the time accurate if the tab is in the background?
This stopwatch uses setInterval to update the display, but it calculates actual elapsed time from the difference between the start time and the current time, so the cumulative time stays accurate even after the tab returns from the background. The on-screen number may simply not update while in the background.
Are recorded lap times saved?
Lap records are kept only in browser memory and are not sent to a server. Refreshing or closing the page clears them. If needed, use the Copy results button to copy the lap list as text to keep it.
Related timers and guides
Last updated: 2026-06-25