Stopwatch

A stopwatch measures elapsed time from a starting point — useful for sports timing, cooking, productivity sessions, experiment durations, presentations, and any activity that needs precise time measurement. Controls: Start — begins counting from zero. The display shows HH:MM:SS.ms in large digits. Stop/Pause — freezes the display at the current time. Resume — continues from the paused time. Lap — records the current time as a split without stopping the main timer. Multiple laps can be recorded. Reset — returns to zero. Clears all lap times. Lap and split timing: Each lap press records two values: the cumulative time (time since start) and the split time (time since the previous lap). Lap times are listed in a table below the main display. This is useful for tracking individual segment times in a race or workout — knowing both that lap 3 was 4:32 and that the total time at that point was 13:47. Export: Export lap data as a CSV file for further analysis in Excel or Google Sheets. Columns include lap number, split time, and cumulative time. Tab title: The running time is shown in the browser tab title so you can monitor elapsed time without keeping the stopwatch tab in focus. Precision: The display updates every 10ms for millisecond visibility. JavaScript timers have approximately 1ms timing accuracy on modern hardware — suitable for practical sports and productivity timing. For laboratory precision timing, hardware stopwatches or dedicated timing equipment provide better accuracy.