Stopwatch
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What Your Result Means
- Elapsed Time: The total time from when you pressed Start, displayed as hours:minutes:seconds.hundredths. Pausing and resuming preserves accumulated time.
- Lap Times: Each lap records the total elapsed time at that moment. To find a split (time between laps), subtract consecutive lap values.
- Precision: The display refreshes every 10 milliseconds (hundredths of a second). Browser timers can drift slightly under heavy CPU load, so for official timing use dedicated hardware.
How This Calculator Works
The stopwatch uses JavaScript's Date.now() to capture a start timestamp and calculates elapsed milliseconds on each refresh cycle (every 10 ms via setInterval). Pausing stores the accumulated time; resuming captures a new start timestamp. Lap records the total elapsed time at the moment the button is pressed. All timing runs client-side in your browser with no network calls.
Quick Questions
How accurate is a browser-based stopwatch?
For casual timing, browser stopwatches are accurate within a few milliseconds. Under heavy CPU load, the display interval may skip frames, but the underlying Date.now() calculation remains accurate. For competition-grade timing, use a dedicated hardware stopwatch.
Will the timer keep running if I switch tabs?
Yes. The timer uses absolute timestamps (Date.now()), so switching tabs or minimizing the browser doesn't affect elapsed time. The display simply catches up when you return.
Can I export my lap times?
Use the "Copy results" button to copy all lap times to your clipboard. You can then paste them into a spreadsheet or notes app for further analysis.
What's the difference between a lap time and a split time?
A lap time is the total elapsed time when the Lap button is pressed. A split time is the difference between two consecutive laps — the duration of that specific segment. This stopwatch records lap times; subtract consecutive values to get splits.
Sources
- MDN — Performance.now() (high-resolution timing in browsers)
- Wikipedia — Stopwatch (timing concepts, lap vs. split)
Method & review
Estimate only. Results reflect your inputs and standard formulas. Double-check important decisions independently.