How to use it
- Press Start (or the Space bar).
- Press Lap (or L) at the end of each lap: a row appears with the lap number, its time and the total so far.
- Press Stop to pause and Resume to continue from the same time.
- Reset clears the time and the laps.
From two laps on, the fastest and the slowest lap are marked in the table. The newest lap is at the top.
How it measures time
The stopwatch remembers when it was started and shows the difference between that moment and now on every screen frame. Time from earlier runs is added when you resume. Because it compares with the clock, a slowed-down background tab cannot make it fall behind. Frames are drawn only while it runs, so a stopped stopwatch uses no processor time.
The display is minutes, seconds and hundredths (02:05.37), and hours appear after the first hour (1:02:05.37). Hundredths are cut, not rounded, so the display never runs ahead of real time.
Worked example
You run three laps and press Lap at 1:15.00, 2:22.00 and 3:40.00 on the stopwatch:
- lap 1: 1:15.00, total 1:15.00;
- lap 2: 2:22.00 − 1:15.00 = 1:07.00 (fastest);
- lap 3: 3:40.00 − 2:22.00 = 1:18.00 (slowest).
The three lap times add up to the last total, 3:40.00.
Tips
- Space on a button. If a button has focus after you clicked it, Space presses that button, as everywhere on the web. Click outside the buttons to use Space for start and stop.
- Precision. Your reaction time is far larger than a hundredth of a second; for fair comparisons, let the same person press the keys.
- Need to count down instead? Use the online timer.