Digital Stopwatch
Precise stopwatch with lap times.
Why use this tool?
Time activities to the hundredth of a second, with lap times for workouts, cooking or presentations.
How to use it
- Click Start.
- Click Lap to record split times.
- Pause or Reset when done.
How it keeps time
The stopwatch shows minutes, seconds and hundredths of a second. It measures elapsed time from the system clock rather than counting ticks, so it stays accurate even if the page is in a background tab, where browsers slow down timers to save battery. The display may update less often there, but the time is correct when you come back.
Lap records the time at that moment without stopping the clock; Pause stops it and Start resumes from where it stopped; Reset clears everything.
Laps and splits
In running and swimming, a split is the total time at a checkpoint and a lap time is the time for one segment. If you record laps at 1:05, 2:12 and 3:16, those are the splits; the individual laps were 1:05, 1:07 and 1:04, which shows whether the pace is steady.
Laps are useful beyond sport: timing each section of a presentation, steps in a recipe or experiment, or how long each round of a game takes.
Accuracy in practice
The clock itself is precise to the millisecond, but human reaction time is the real limit: pressing a button at the right instant is usually accurate to about 0.1-0.2 seconds. That's fine for training and everyday timing, which is why official races use automatic timing systems instead.
For best results, keep your finger or cursor ready on the button, and have the same person start and stop each time so reaction delays roughly cancel out.
Frequently asked questions
Does it keep running in a background tab?
Yes. Time is measured from the system clock, so it stays accurate even when the tab isn't visible.
How precise is it?
It displays hundredths of a second. In practice, human reaction time (about 0.1-0.2 s) limits accuracy when timing by hand.
What's the difference between a lap and a split?
A split is the total elapsed time at a point; a lap is the time for one segment between two points.