A precise stopwatch with lap tracking, split times, and exportable results.
Click the start button to begin timing.
Click lap to record split times without stopping the watch.
Press stop to pause or reset to clear the timer.
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.
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.
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.
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.
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.
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.
The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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