When to use Stopwatch
Use it when you need elapsed time rather than a countdown, including laps or repeated attempts.
How to use Stopwatch
Set the inputs that matter for this task, run the tool, then copy or reuse the result when the page offers that action. Inputs stay visible so you can adjust them and run the tool again without starting over.
Timing behavior
Running time is derived from timestamps rather than counting interval ticks, so the display can correct itself after normal browser throttling.