How to use the stopwatch
- Start with the button or Space. The title of the tab shows the running time, so you can see it from another tab.
- Record laps with Lap, L or Enter. The fastest and slowest laps are highlighted.
- Stop and resume as often as you like; Reset clears the time and the laps when stopped.
- Big view (F) fills the window with large digits; Download CSV keeps the laps.
Why it stays accurate in the background
Many web stopwatches add a fixed amount each time a timer fires. Browsers deliberately slow timers in tabs you are not looking at to save battery, and Chrome can limit a hidden tab to about one timer check per minute after a few minutes, so those stopwatches lose time while you are away. This one never counts ticks: it keeps the moment it was started and the time built up before any pause, and computes the elapsed time from the clock whenever it draws. Laps are stored as totals, and lap times are the differences between them, so rounding never accumulates.
What we tested
On October 14, 2026 we ran the stopwatch in Chromium with a controlled clock, including a hidden-tab case where timers fired only once a minute, and checked laps, pause and resume, reload and the CSV export.
| Test | Result |
|---|---|
| 5 seconds of normal running | 00:04.98 on screen (the display redraws every 33 ms; the recorded lap at that moment was exactly 00:05.00) |
| Laps at 5.00, 12.50 and 18.50 s | lap times 00:05.00, 00:07.50, 00:06.00; fastest and slowest marked |
| 10 minutes with timers firing only once a minute (hidden tab) | 10:18.50 (expected 10:18.50) |
| Stopped, then 60 seconds pass | 10:18.50 before, 10:18.50 after |
| Resumed for 2 seconds | 10:20.48 |
| Reload while running (real clock, 1.5 s) | 00:02.17, still running |
| CSV | 3 lap rows with times and milliseconds |
The page fitted a 390 px phone screen with no errors.
Sources
Checked on .
Frequently Asked Questions
Built by Derek Giordano · Part of Ultimate Design Tools