Online stopwatch

About this stopwatch

This stopwatch runs entirely in your browser. There is nothing to install, no account to create, and no cost — press Start and it begins timing immediately, down to a hundredth of a second.

How to use it

Press Start to begin. The button becomes Stop, and pressing it pauses the clock; pressing Resume continues from exactly where you stopped rather than starting over. Reset clears the clock and any recorded laps back to zero.

Lap is the one worth understanding. Pressing it records the time at that moment without interrupting the running clock. Each entry shows two numbers: the split (how long that individual lap took) and the total elapsed time when it was recorded. That distinction matters when you are timing something repeated — a runner’s individual lap times tell you a different story from their cumulative time.

What people use it for

• Interval training — timing work and rest periods, or recording each round without stopping the clock.
• Classrooms — timing activities, tests, and group work on a screen the whole room can see.
• Sports and coaching — lap times for running, swimming, and cycling.
• Presentations and interviews — keeping to an allotted time.
• Cooking — timing steps that need watching rather than a fixed countdown.
• Science and lab work — recording elapsed time at each stage of an experiment.
• Music practice — timing scales, drills, or how long a piece runs.

Why it stays accurate

Many browser stopwatches count upward one tick at a time, which drifts badly the moment you switch tabs — browsers deliberately slow down pages that are not in view to save battery, so those ticks stop arriving on schedule.

This one measures elapsed time against your device’s clock instead. Switching tabs, opening another window, or leaving it running in the background does not affect the reading; when you come back, the time shown is correct.

Common questions