Stopwatch
Precise stopwatch with millisecond accuracy and lap tracking.
Time an activity to the millisecond, record lap splits, and compare your fastest and slowest laps.
Press Start to begin timing. The large display shows HH:MM:SS.mmm and updates at your screen refresh rate.
Press Lap to record the current elapsed time as a split without stopping the clock. Each lap appears at the top of the lap list.
Press Pause to stop the stopwatch; press Start again to resume where you paused. Lap times are preserved across pauses.
Press Reset to clear the elapsed time and delete all laps. Use this when you want to start a new timing session.
Read the lap list: the fastest lap is highlighted green and the slowest is highlighted red once you have two or more laps.
- How precise is the stopwatch?
- Timing is measured with Date.now() deltas, which gives millisecond accuracy. The display updates at your screen refresh rate (typically 60 frames per second) and shows milliseconds directly.
- Will the stopwatch drift if I leave the tab running in the background?
- No. Elapsed time is calculated from the start timestamp plus any accumulated offset, not by counting ticks, so browser background-tab throttling has no effect on accuracy.
- Can I keep my laps when I pause and resume?
- Yes. Pause and resume preserve all recorded laps. Laps are only cleared when you press Reset.
More time tools
Set a timer for any duration. Get an alert when time is up.
TimerConvert times between any IANA timezones with DST awareness.
TimezoneWork in focused intervals with automatic break scheduling.
ProductivityTrack the current time in multiple cities at a glance.
ClockConvert Unix epoch timestamps to dates and back, in seconds or milliseconds.
DateCalculate exact age in years, months, days, hours, and seconds.
DateAdd or subtract from a date, or measure the duration between two dates.
DateRun work/rest intervals for HIIT, Tabata, and circuit workouts.
TimerSet multiple alarms with labels, audio, and desktop notifications.
TimerFind the best meeting time across timezones on a 24-hour overlap grid.
TimezoneCalculate sunrise, sunset, twilight, and golden hour for any location.
TimezoneTwo-player chess clock with Fischer increment and Bronstein delay.
Productivity