Stopwatch
Stopwatch — runs in your browser. Inputs are not stored.
Stopwatch
Enter values, then press Calculate.
Measure with start, stop, lap, and reset. Data is not sent to the server.
How to use
- Press Start and the time field counts up from 00:00:00.0. Digits are hours:minutes:seconds and tenths of a second.
- Press Lap while running to stack that moment’s cumulative time as a line in the lap log and increase the lap count.
- Press Stop to freeze the digits; Start again to continue. Stop alone does not clear laps.
- Lap is not recorded in idle state before the first Start. Press it after timing has begun.
- Reset clears time, lap count, and the lap list. Use it to time from scratch.
- The lap log is read-only. Do not edit lines; copy the text into a notes app if you need it.
Key concepts
An online stopwatch measures elapsed time from start until now. Laps on this screen are cumulative times at that moment, not split times for a segment. To see one-lap duration, subtract two adjacent lap lines.
After Stop, Start continues the accumulated elapsed time. Data stays in the browser and is not sent to a server. Background tabs may slow updates, so do not use it as an official race clock. Lap count matches the number of list lines, and the list remains if you Stop several times until you Reset. It is not for matching an official race clock or referee record.
Example
For 400 metres in four 100-metre splits, Start and press Lap at each 100 metres. Lines such as Lap 1 and Lap 2 stack cumulative times. Subtract the first line from the second for the second 100-metre split. When the workout ends, Stop and copy the list. For swim splits, laps are still cumulative, so get used to subtracting the previous lap when you fill a log.
Related: Timer alarm · Repeat timer · Count-up timer
Frequently asked questions
Is a stopwatch lap a split or a cumulative time?
Cumulative elapsed time. The lap log writes the full time at that moment, such as Lap 1 and Lap 2. Subtract adjacent lines for a split.
Can I add a lap after stopping the stopwatch?
If a measurement already exists, you can add another lap line while stopped. At 0 seconds before any Start, nothing is recorded.
Does the stopwatch show tenths of a second?
Yes. Display is hours:minutes:seconds and one decimal place. Full milliseconds are not shown.
Do stopwatch records remain on a server?
No. Closing the tab or pressing Reset also clears the lap list.
Should I use the timer alarm or the stopwatch?
Use the timer alarm to count remaining time and beep at the end; use the stopwatch to measure time already elapsed.
Is the stopwatch right for repeating interval workouts?
If you need the same seconds each round and a beep, the repeat timer fits better. The stopwatch is for free timing and a lap list.
Last reviewed: 2026-09-04