Stopwatch
Online stopwatch with lap times.
Using the stopwatch effectively
Click Start to begin timing, Lap to record an intermediate time without stopping the clock, and Stop to pause. Lap times show both the cumulative time and the split time (time elapsed since the previous lap). This lets you track individual segments — for example, laps in a race or timed sections of a presentation.
How digital stopwatches work
This stopwatch measures elapsed time in milliseconds using the browser's high-resolution Date.now() API, which reads the system clock. The display updates every 50ms for smooth rendering. The saved offset technique ensures pausing and resuming accumulates time correctly without drift.
Common stopwatch applications
Reading lap splits: how to analyse your times
The cumulative time shows total elapsed time at each lap. The split (shown in grey next to each lap) shows only the time for that individual segment. In running, an even split strategy — where each lap takes roughly the same time — is generally more efficient than going out too fast. Positive splits (getting slower) usually indicate premature exhaustion; negative splits (getting faster) are often optimal.
Frequently asked questions
Can I record lap times?
Yes. The stopwatch lets you capture lap or split times while it keeps running, so you can compare intervals.
Is the stopwatch accurate?
It measures real elapsed time using your device clock, which is accurate to the millisecond for everyday timing needs.
Does it keep timing if I switch tabs?
Yes. Timing is based on real time, so leaving or returning to the tab does not affect the measured duration.
What is the difference between a stopwatch and a timer?
A stopwatch counts up from zero to measure how long something takes; a timer counts down from a set duration to zero.
A full-featured online stopwatch with lap time tracking. Records split times with the delta between each lap. Works entirely in your browser.