Stopwatch vs timer — which do you need?
A stopwatch counts up from zero and answers "how long did that take?" — intervals, laps, speedruns, how long the kids brushed their teeth. A timer counts down to an alarm and answers "tell me when it's been N minutes." For the second kind, use the countdown timer or a preset.
Getting useful data from laps
Press Lap at every meaningful boundary — each interval, each set, each lap of the track — without stopping the clock. Afterward, the spread between green and red laps measures your consistency: sprinters aim for tight spreads; a widening red tail signals fatigue. For pace work, the cumulative column tells you whether the whole session hit its target time.
Frequently asked questions
How accurate is this online stopwatch?
Elapsed time is measured from your device's clock (Date.now), not by counting animation frames, so it stays accurate to a few milliseconds regardless of tab activity or device load — displayed to the hundredth of a second.
What do the green and red laps mean?
Once you've recorded two or more laps, the fastest lap is highlighted green and the slowest red — instant feedback for interval training and time trials.
Does the stopwatch keep running if I close the tab?
Switching tabs is fine — timing continues. Closing the tab ends the session, since nothing is stored or sent anywhere by design.
Can I use it for swimming or track workouts?
Yes — Start at the gun, Lap at each split, Stop at the finish. The table keeps both individual lap times and cumulative totals, newest on top.