Stopwatch

The Online Stopwatch is a precision tool for measuring time intervals directly in your browser. With centisecond resolution, it displays hours, minutes, seconds, and hundredths in real time, updated frame by frame via requestAnimationFrame — ensuring smooth animation without freezing the tab.

To use it, click "Start" to begin the count. Use "Lap" during timing to record a split for each segment without interrupting the stopwatch — all laps are listed below the display. When you need to pause, click "Pause"; the accumulated time is preserved and timing resumes exactly where it left off. "Reset" restarts everything, including the lap history.

Common use cases include physical training (running, swimming, HIIT intervals), study sessions using the Pomodoro technique or timed blocks, amateur sports competitions, timed presentations with a hard cutoff, and school lab experiments that require precise elapsed time. Any activity that requires measuring how long something takes has a simple, immediate solution here.

Everything runs entirely in the browser: no data is sent to servers, no account is needed, and nothing needs to be installed. The stopwatch works on computers, tablets, and smartphones — just open the page.