Stopwatch
What you enter stays on your device while you use this tool. Opening a shared link sends the settings in its address to HowToolbox to prepare the page.
Ready
Normal view. Keep-awake is off.
Keys: Space = start or stop · L = lap · R = reset
Lap summary
- Laps
- 0
Select Lap while the stopwatch runs to record a lap.
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Start, lap, stop: every split kept.
How to use
- Select Start. The time counts up in hundredths of a second.
- Select Lap at each lap, length or checkpoint. The table shows the lap time, the total so far and marks the fastest and slowest laps.
- Select Stop to hold the time and Continue to carry on. Reset clears the time, the laps and the saved copy.
- Copy the lap table or download it as CSV for a spreadsheet. Open full screen for a large display. On a keyboard, Space starts or stops, L records a lap and R resets.
How it works
A stopwatch measures how much time passes between Start and Stop. It notes the moment you select Start and, whenever it shows the time, subtracts that moment from the current one. Stopping keeps the total; continuing adds the next stretch on top.
Selecting Lap records a split: the total time on the watch at that moment. A lap time is the difference between two neighbouring splits: lap n = split n − split n−1. With splits of 1:05.20 and 2:08.90, the second lap took 2:08.90 − 1:05.20 = 1:03.70.
The time comes from your device's steady, high-resolution clock, so it stays right even if the page sleeps in a background tab. After a reload the stopwatch adds the time that passed using the device clock, so changing that clock can shift a saved session. Your reaction time when pressing the buttons is usually a larger error than the clock.
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Frequently asked questions
What is the difference between a lap and a split?
A split is the total time when you selected Lap. A lap time is how long that one lap took: the split minus the previous split.
Does it keep running if I close the tab?
If saving on this device is available, yes: reopen the page and the stopwatch shows the time that has passed, with your laps. Reset removes the saved copy.
How are fastest and slowest laps marked?
From two laps on, the quickest and slowest lap times get a written Fastest or Slowest note, so the marking never depends on colour.
How precise is it?
The display shows hundredths of a second, and the CSV keeps milliseconds. Pressing a button by hand typically adds more delay than the clock itself.
Can I export my lap times?
Yes. Download the lap table as CSV, or copy it to paste into a spreadsheet.
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