Stopwatch

A precise stopwatch with lap tracking, split times, and exportable results.

How to Use Stopwatch

1

Press start

Click the start button to begin timing.
2

Record laps

Click lap to record split times without stopping the watch.
3

Stop and reset

Press stop to pause or reset to clear the timer.

Tested tool guide Tested browser tools Checked August 16, 2026

What Stopwatch does, with a checked example

A stopwatch exists to answer one question - how long did that take - and this one answers it with a display that counts upward in hundredths of a second until you stop it. Its real value is what happens between Start and Stop: every press of Lap stamps the current moment into the results list without pausing the clock. Each entry records the segment since the previous press and the running total, so one run produces a complete timeline of a workout, a task, or a process. The results can be exported when the run ends, turning the stopwatch into a small data recorder.

Worked example

A concrete input and expected output from the current implementation.

Input

Start the watch, press Lap at 1:30.00, press Lap again at 3:10.00, then press Stop at 4:00.00.

Expected output

Lap 1: 1:30.00 (total 1:30.00)
Lap 2: 1:40.00 (total 3:10.00)
Stopped: 4:00.00 elapsed

Lap 1 is the segment from Start to the first press. Lap 2's 1:40.00 is the difference between the two presses (3:10.00 minus 1:30.00 = 1:40.00), while its total of 3:10.00 counts from Start. The stop time of 4:00.00 is the full duration of the run.

How the result is produced

Start, Lap, Stop

Press Start and the display begins counting upward; pressing Lap immediately adds a row to the results list while the clock keeps running. You can press Lap as often as needed - at each lap of a track, each step of a process - and the watch never pauses on its own. Stop ends the run and the list is complete.

Reading the results

Every row in the results list carries two numbers: the lap, the time since the previous press (or since Start for the first row), and the total, the time since Start. The total of the last row is the overall run time. Because each lap feeds the next total, the lap column adds up exactly to that final total, which is a quick self-check when reading the table.

Good uses

Track a running workout - press Lap at the end of each circuit or interval, then compare segment times to see whether your pace holds or drifts across a session.
Split a task into measurable stages - time a recipe, a code build, or a presentation section by section, pressing Lap at each boundary to learn how long every phase takes without stopping the clock.
Record a session for the record - time an experiment, a phone-support call, or a batch job and export the lap list afterward so the numbers land in a file or spreadsheet instead of living in your head.

Limits and checks

The lap number is the segment since the previous press, not the time since Start. Only the total column is cumulative, so a lap of 1:40.00 followed by a total of 3:10.00 means the second press came 1:40 after the first, not 3:10 into the run.
Times are shown as m:ss.cc. A result of 1:30.00 is one minute thirty seconds, not one point three seconds; the leading minutes digit is the giveaway. With a long run, double-check the minutes place before quoting a number.
The stopwatch times your presses, not the physical event: a hand-tapped Lap can land a couple of tenths of a second after the moment you meant to mark. And a browser tab left in the background for a long stretch can have its timing throttled, so keep the stopwatch visible when the run must be exact.

Common questions

Does pressing Lap pause the timer?

No - that is the point of a lap. Lap records the current segment and the clock keeps running, so you can mark as many boundaries as you like without losing time. Stop halts the run, and Reset clears the recorded list so the next run starts from zero.

What is the difference between a lap and a split?

In stopwatch vocabulary the two words are often used interchangeably, and the tool's own description lists both for the same reason. What matters is the two numbers on each row: the segment since the last press and the running total since Start. Before quoting a result, check which of the two you are looking at.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.