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Online Stopwatch

Start a precise count-up stopwatch with lap splits — free, private, and instant in your browser.

Privacy: your files never leave your device. All processing happens locally in your browser.

How to use

  1. 1.Press Start to begin counting up from zero — the large display shows minutes, seconds, and hundredths of a second.
  2. 2.While it runs, press Lap to record a split; each lap shows that segment's time and the cumulative total, newest at the top.
  3. 3.Press Pause to freeze the time, then Resume to continue exactly where you left off.
  4. 4.Press Reset to clear the elapsed time and all recorded laps back to zero for a fresh measurement.

About Online Stopwatch

An online stopwatch is the simplest way to measure how long something takes. Press Start and the timer counts up from zero — minutes, seconds, and hundredths of a second — until you pause or reset it. Unlike a countdown timer that runs down to zero, or a Pomodoro timer that cycles through fixed focus and break blocks, a stopwatch has no preset duration: it measures the real, open-ended time an activity actually consumes, which makes it the right tool whenever you do not know in advance how long you will need.

That covers a surprising range of everyday tasks. Runners, swimmers, and cyclists time intervals, sprints, and full sessions. Students and knowledge workers time focused study blocks or track exactly how long a task takes so they can plan better next time. Cooks time a boil, a rest, or a brew without hovering over the oven clock. Public speakers and interviewees rehearse to a target length and watch the elapsed time climb. Anyone doing timed exercises, plank holds, breathing routines, or workout circuits can glance at the large display from across the room.

The Lap feature is what sets a stopwatch apart from a plain clock. While the timer is running, press Lap to freeze the current moment without stopping the clock. Each lap records two numbers: the split — how long that individual segment took — and the cumulative total from the moment you started. That lets you compare segments directly: which lap of a run was fastest, how long each phase of a multi-step task took, or where a rehearsal ran long. Laps are listed newest-first so the most recent split is always at the top, and Reset clears everything back to zero when you are ready for a fresh measurement.

Precision matters for short intervals, so this stopwatch shows hundredths of a second (centiseconds). For sprints, reaction drills, or anything under a minute, that extra resolution is the difference between a useful measurement and a rounded guess. Once the elapsed time passes an hour the display automatically switches to an hours:minutes:seconds format so long sessions stay readable.

Accuracy is handled with anchored timing rather than naive tick counting. The stopwatch records a high-resolution start reference and, on every refresh, recomputes the elapsed time as the accumulated total plus the real gap since that reference. Because each frame is recalculated from the true clock instead of adding up individual ticks, the reading does not drift, and it does not fall behind when your device throttles background tabs. If you switch to another tab and come back, the display corrects itself to the genuine elapsed time. Pausing freezes the accumulated total precisely at the click; resuming continues from that exact value.

Everything runs locally in your browser. There is no account, no sign-in, and no network request — your timing never leaves your device, so it is completely private and works even offline once the page has loaded. Bookmark it as a fast, distraction-free replacement for a phone or physical stopwatch whenever you need to measure elapsed time with lap splits.

Frequently asked questions

Does it keep timing if I switch tabs?
Yes. The stopwatch uses anchored timing: instead of counting individual ticks, it recomputes elapsed time from a real start reference on every refresh. When you return to the tab, the display corrects itself to the true elapsed time, so background throttling never makes it drift or fall behind.
What is a lap?
A lap freezes the current moment without stopping the clock. Each lap records two values: the split (how long that individual segment took) and the total (cumulative time since you pressed Start), so you can compare segments against each other.
Is it accurate to hundredths of a second?
Yes. The display shows centiseconds — hundredths of a second — which is useful for sprints, reaction tests, and any short interval. The reading is computed from a high-resolution clock, and once you pass one hour the format switches to hours:minutes:seconds for readability.
How is this different from a countdown or Pomodoro timer?
A stopwatch counts up from zero with no preset duration, so it measures open-ended elapsed time. A countdown timer runs down from a duration you set to zero, and a Pomodoro timer cycles through fixed focus and break intervals. Use the stopwatch when you do not know in advance how long the activity will take.
Is my data uploaded anywhere?
No. The stopwatch runs entirely in your browser with no account and no network requests. Your timing and laps never leave your device, and the tool works offline once the page has loaded.

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