Stopwatch

How to use it

• Start begins timing. The button changes to Stop, which pauses it. Press Start again to carry on.
• Lap records the current time without stopping the clock. Laps are listed with the newest first.
• Reset clears the time and all laps.

Reading the display

The display shows minutes, seconds and hundredths of a second, like this: 02:15.37 means 2 minutes, 15 seconds and 37 hundredths. After an hour, the hours appear at the front.

Lap times

Each press of Lap adds a row with three figures:

Column	Meaning
Lap	The lap number
Lap time	Time taken for that lap alone
Total	Time on the clock when the lap ended

Example: a runner passes you at 1:32.10, 3:01.45 and 4:35.20. The lap times are 1:32.10, then 3:01.45 − 1:32.10 = 1:29.35, then 4:35.20 − 3:01.45 = 1:33.75.

How it works

The stopwatch notes the reading of the browser’s high-resolution timer when you press Start and subtracts it from the current reading each time the screen redraws. That timer is not affected by changes to the device’s clock, such as an automatic time correction.

Limits

• The display updates about 60 times a second, so the last digit jumps rather than counting every hundredth.
• Times and laps are lost if you reload or close the page.
• Hand timing is not accepted for official athletics records, which use electronic systems triggered by the starting signal.
• If the device goes to sleep, timing may pause, depending on the device.