What is a lap time on a stopwatch?

A lap time records the elapsed time at a specific moment without stopping the stopwatch. It shows both the split (time since the last lap) and the cumulative time from start. Lap times are useful for tracking interval times in running, swimming, or any repeated activity.

Will the stopwatch pause if I switch tabs?

No. This stopwatch uses Date.now() to calculate elapsed time, not interval counting. Even if the browser throttles JavaScript in background tabs, the elapsed time calculation remains accurate because it measures wall-clock time from when you started.

Online Stopwatch - Free with Lap Timer

Q: How accurate is this online stopwatch?

This stopwatch displays centiseconds (1/100th of a second) and uses Date.now() for timing, which is accurate to the millisecond in modern browsers. The display updates every 10ms. Note that browser JavaScript timing can have slight jitter of a few milliseconds, so for professional timing use a dedicated hardware stopwatch.

Q: What are the keyboard shortcuts?

Space bar starts or stops the stopwatch. L records a lap while running. R resets the stopwatch when it is stopped. These shortcuts work when the page is focused and no text input has focus.

Q: How many laps can I record?

There is no hard limit — you can record as many laps as needed. All laps are shown in the scrollable list below the buttons with their lap number, split time, and cumulative time.

What Is a Stopwatch?

A stopwatch is a timing instrument that measures elapsed time from a start point. Unlike a clock that shows the current time, a stopwatch counts up from zero. Stopwatches are used in sports timing, cooking, fitness training, productivity techniques (like the Pomodoro method's inverse), science experiments, and anywhere you need to know how long something took.

How to Use This Online Stopwatch

Click Start to begin timing. The display shows minutes, seconds, and centiseconds in MM:SS.cc format. While running, click Lap to record the current time without stopping — this adds a row to the lap table showing the split time (time since the last lap) and the cumulative time. Click Start again (which becomes Stop) to pause. Click Reset to clear everything back to zero.

Lap Times Explained

Each lap row shows three values:

Lap #: Sequential number of the recorded lap.
Split time: Elapsed time since the previous lap (or from start for the first lap). Use this to compare interval times.
Cumulative time: Total elapsed time from start at the moment you pressed Lap. Use this as an absolute reference.

Common Uses

Running and fitness: Time intervals, rest periods, and track splits for each lap of a run.
Cooking: Time recipe steps precisely when accuracy matters.
Presentations: Monitor elapsed time during a talk to stay on schedule.
Productivity: Track how long tasks actually take versus estimated time.
Science: Time experiments or reactions with centisecond precision.

Frequently Asked Questions

How accurate is this online stopwatch?

It displays centiseconds (1/100th of a second) and uses Date.now() for timing — accurate to the millisecond. The display refreshes every 10ms. Browser JavaScript has slight timing jitter of a few milliseconds, so for professional athletics use a hardware stopwatch.

What is a lap time?

Pressing Lap records the current time without stopping. It shows the split (time since last lap) and cumulative time (total from start). Laps are useful for tracking each repetition of a repeated activity like running intervals or set times in a workout.

What are the keyboard shortcuts?

Space starts or stops the stopwatch. L records a lap (while running). R resets (while stopped). Shortcuts work when the page is focused and no text input is active.

Will it pause if I switch browser tabs?

No. The stopwatch uses Date.now() to calculate elapsed time, not event counting. Even if the browser throttles background JavaScript, the elapsed time remains accurate because it measures actual wall-clock time from when you started.

How many laps can I record?

There is no limit. All laps are displayed in the scrollable table with their number, split time, and cumulative time. The most recent lap always appears at the top.