Stopwatch

Related guide

Countdown, Pomodoro and Stopwatch: Which One Still Keeps Time in a Hidden Tab
The stopwatch recomputes the elapsed time from the system clock every 20 ms, so a throttled tab cannot make it lose a second; the countdown and the Pomodoro timer count ticks instead and fall behind. Measured on the pages: a finished countdown restarts in one press while the Pomodoro timer needs two, a 200-minute focus block is accepted despite the field saying 120, and a negative entry leaves 0-5:00 on screen.

What the display shows

The readout is minutes, seconds and hundredths of a second — 02:47.63 means two minutes, forty-seven seconds and sixty-three hundredths. There is no hours field, so a run lasting more than an hour keeps growing in the minutes position rather than rolling over into hours; 75 minutes reads as 75:00.00.

Start begins a run, and the same button pauses it and resumes it without losing elapsed time. Reset clears the clock and the lap list together and is the only control that discards a run.

Recording laps

Lap is available while the timer is running and greyed out while it is paused, which avoids the commonest misreading of a split-time stopwatch: laps recorded against a stopped clock, all showing the same total. Each lap stores the running total at the moment you pressed the button rather than the segment on its own.

The list renders three things per row — the lap number, the split for that lap, and the cumulative time from the start. Splits are worked out by subtracting one total from the next, and once you have three or more laps the fastest and slowest splits are marked, which is the part that is actually useful for pacing: averages hide variation, and the spread is what tells you whether your pace is holding.

If two laps share the fastest split, both are marked. The comparison only kicks in from the third lap, because with one or two laps there is nothing meaningful to compare against.

Why this one does not drift

The stopwatch does not count ticks. Each refresh it recomputes the elapsed time from the current clock reading minus the moment the run started, so the number it displays is derived from real time rather than accumulated. Leave the tab, come back, and the display jumps straight to the correct total instead of being however many seconds short the throttled timer missed.

The display refreshes about fifty times a second, comfortably faster than the eye can follow, though the resolution you should trust is the hundredth of a second shown. For anything where the timing itself matters more than the convenience — official results, calibration, anything with a rulebook — use a dedicated timer or a hardware stopwatch; a browser is not a measurement instrument.

FAQ

How do I read a lap row?
The number is the lap, the middle figure is how long that lap took on its own, and the right-hand figure is the total elapsed when the lap was recorded. To get a segment, subtract one total from the next — which is what the middle column has already done for you.

Why are some laps highlighted?
From the third lap on, the fastest and slowest splits are marked so the pattern is visible at a glance. With only one or two laps there is not enough to compare, so nothing is highlighted.

Why is the Lap button greyed out?
Laps can only be recorded while the clock is running. Press Start first. This prevents a list of identical splits from being recorded against a paused stopwatch.

Does it lose time if I switch to another tab?
No. The elapsed time is recalculated from the system clock rather than accumulated tick by tick, so a throttled background tab does not lose anything. The display may not update while the tab is hidden, but it corrects itself the moment it comes back.

Can it time something longer than an hour?
Yes, it just displays the total in minutes. Ninety minutes reads as 90:00.00. There is no hours field and no rollover, so nothing is lost — only the formatting is unusual.

Is there a keyboard shortcut?
The page does not define one, so space and the arrow keys behave as the browser normally would. Use the buttons, and keep the tab visible if you are timing something you will not be watching directly.