Online Stopwatch

Most quick-and-dirty browser stopwatches count screen frames or add a fixed amount on a repeating timer, which means they slowly drift — especially if the tab is backgrounded or the browser throttles its timers. This one works differently. When you press Start it records the exact clock time; every reading after that is the difference between the clock now and that start point, plus any time already banked from earlier runs. The on-screen number refreshes smoothly many times a second for a live feel, but the value it shows is always derived from the real system clock, so it is accurate to the hundredth of a second no matter what the browser does in the background. Stop and start as often as you like — the elapsed total is preserved each time, so you can pause and resume without losing your place.

The Lap button is what turns a stopwatch into a real training and analysis tool. Each time you tap it, the clock keeps running but a new row is recorded showing two numbers: the lap time, which is how long that single segment took, and the total time, the full elapsed time so far. For a runner doing 400-metre repeats, the lap times reveal whether each interval is consistent while the total tracks the whole workout; for anything done in stages — cooking, experiments, multi-part tasks — the laps give you a clean timeline of how long each phase actually took. This tool highlights your fastest lap in green and your slowest in red so the pattern jumps out at a glance. Everything stays on screen until you reset, and you can keep lapping for as long as you need.

Start, stop, lap, and reset with the buttons or the keyboard (Space, L, R). The clock is accurate to a hundredth of a second, survives background tabs, and runs entirely in your browser — nothing is timed on a server and nothing is uploaded. Need to count down instead of up? Use the Countdown Timer, or structure focused work with the Pomodoro Timer.