⏱️Online Stopwatch with Laps
Centisecond precision — tap start, record laps, see fastest and slowest highlighted.
Need to time something precisely? Our free online stopwatch with laps starts the moment you tap go. A big, clear display counts up to the centisecond, and you can stop, resume, and reset whenever you need — no app, no setup, just an accurate stopwatch ready in your browser.
What makes it handy is laps. Tap the lap button to record a split without stopping the clock, and each lap is listed with its own time and the cumulative total, so you can compare segments at a glance. The fastest and slowest laps are highlighted automatically, which is perfect for timing workouts, runs, intervals, races, experiments, or anything with repeated rounds. The screen stays awake while it runs, so your timing never gets interrupted mid-session.
Simply tap start to begin timing. No sign-up, no downloads, no limits — just a precise stopwatch online whenever you need it.
About the Online Stopwatch with Laps
Laps vs splits
Lap time
The duration of a single segment — the time since your last lap tap. Useful for comparing individual intervals, rounds, or legs of a race.
Split (cumulative)
The total elapsed time at the moment the lap was recorded. Useful for knowing when each segment finished within the overall session.
Key features
Centisecond display
Shows HH:MM:SS.cc — hours, minutes, seconds, and hundredths — for precise timing at any scale from a second to hours.
Lap table
Each tap of the Lap button records the lap number, individual lap duration, and cumulative split in a scrollable table.
Fastest & slowest
When two or more laps exist, the best lap is highlighted in green and the slowest in red — no counting needed.
Drift-free engine
Uses performance.now() timestamp anchors, not frame counting, so elapsed time stays accurate over long runs and when the tab is throttled.
Screen wake lock
Requests a wake lock on supported browsers while running, preventing the screen from dimming mid-session. Degrades gracefully elsewhere.
Stop & resume
Pause the clock at any moment and pick up exactly where you left off — paused time is excluded from the elapsed total.
Common uses
Workouts & runs
Record lap times for each interval, lap, or set. See at a glance which effort was fastest and which was slowest.
Races & competitions
Time multiple competitors or track splits across legs of a relay — the cumulative split shows finish times without mental arithmetic.
Lab & experiments
Record reaction times, process durations, or trial intervals with centisecond resolution and a clear table to review afterward.
Presentations & speeches
Tap Lap at each section to track how long each part took — useful for rehearsing talks with time targets per segment.
Frequently Asked Questions
How does the online stopwatch work?
Tap Start and the stopwatch counts up from zero. Tap Lap at any point to record a split without stopping the clock. Tap Stop to pause, Resume to continue, and Reset to clear everything and start over.
Is the stopwatch free to use?
Completely free — no sign-up, no downloads, no limits. Use it as many times as you like on any device.
What is the difference between a lap time and a split?
A lap time is the duration of one segment — the time elapsed since your last lap tap. A split (cumulative) is the total elapsed time at that lap point. The table shows both: lap time in the middle column, cumulative split on the right.
Does it highlight my fastest and slowest lap?
Yes. Once you have two or more laps, the lap table automatically marks the fastest lap in green and the slowest lap in red so they're easy to spot at a glance.
How precise is the stopwatch?
The display shows centiseconds (hundredths of a second). Timing is based on performance.now() timestamp anchors rather than accumulated tick counts, so it stays accurate over long sessions.
Will it stay accurate if I switch tabs?
Yes. Because the stopwatch measures elapsed time from a start timestamp rather than counting animation frames, it doesn't drift when the browser throttles background tabs. The displayed time catches up the moment you return to the tab.
Does the screen stay on while the stopwatch is running?
On browsers that support the Screen Wake Lock API (Chrome, Edge, and others), the stopwatch requests a wake lock when you tap Start to prevent the display from turning off. A small badge confirms when the wake lock is active. It degrades gracefully on unsupported browsers.
Can I reset and start over?
Yes. Tap Reset at any time to zero the elapsed time and clear all recorded laps. The stopwatch returns to its initial state, ready for a fresh run.
Is any data stored or sent anywhere?
No. The stopwatch runs entirely in your browser. Nothing is stored, logged, or sent to a server. Close the tab and all lap data is gone.
Does the stopwatch work on mobile?
Yes. It's fully responsive with a large readable display and large tap targets for Start and Lap buttons. It works on phones, tablets, and desktops without any installation.