Track elapsed time against a monotonic browser clock without losing progress when rendering slows.
00:00:00.00
Lap
Lap time
Total time
Method
Time and calendar calculation method
Stopwatch elapsed time uses a monotonic high-resolution browser clock. Calendar results use Gregorian and ISO rules, while lunar and solar results apply documented mean-cycle and coordinate formulas.
Astronomical output is an estimate. Coordinates, elevation, refraction, local terrain, the entered UTC offset, and the simplified lunar model can change observed or high-precision event times.
Questions
Online Stopwatch FAQ
How precise is the stopwatch?
It uses performance.now, a monotonic high-resolution browser clock, and displays hundredths of a second. Device scheduling can still affect button timing.
Will the stopwatch run in a background tab?
The displayed animation may update less often, but elapsed time is recalculated from the clock when the tab becomes active again.
