How to use the stopwatch
- Press Start (or the space bar) to begin timing.
- Press Lap (or L) each time you want to record a lap or a split, without stopping the clock.
- Press Stop to pause. Resume carries on from the same time, and Reset clears everything.
- Use Copy lap times to paste your results into a spreadsheet, notes app or message. They paste as neat columns.
The stopwatch measures time with your device's high-precision clock, so it doesn't drift and stays accurate if you switch tabs. The display shows hundredths of a second. In practice, the limit on accuracy is your reaction time when pressing the button, which is usually around 0.2 seconds.
Lap time or split time?
A lap time is how long one lap took on its own. A split time is the total time from the start up to that point. If you run three laps of 1:30, 1:35 and 1:28, your lap times are those three figures, and your splits are 1:30, 3:05 and 4:33. The table shows both, with your fastest lap in green and your slowest in red once you've done three or more.
What people time with a stopwatch
- Running and athletics: track laps, interval sessions and parkrun practice. Turn your times into pace with the running pace calculator.
- Swimming: lengths and rest intervals.
- School science: pendulum swings, reaction times and how long a reaction takes to finish. Timing 10 swings and dividing by 10 gives a more accurate result than timing one.
- Presentations and speeches: rehearse to check you finish in time. Use the word counter to estimate speaking time from your script.
- Cooking and brewing: when you want to know how long something has taken rather than count down. For countdowns, use the online timer.
- Work tasks: timing jobs to price your work more accurately. The hours calculator adds up hours worked.
Full screen
Press Full screen (or F) to show a large stopwatch that can be read from across a room, sports hall or classroom. Press Escape to go back.
Frequently asked questions
How accurate is the online stopwatch?
It measures time with your device's high-precision clock and shows hundredths of a second. The main source of error is human reaction time when pressing the buttons, typically about 0.2 seconds.
How do I record laps?
Press Lap (or L on your keyboard) while the stopwatch is running. Each lap time and the total time so far are added to the table.
What's the difference between a lap and a split?
A lap time is how long that one lap took. A split time is the total elapsed time from the start to the end of that lap.
Does the stopwatch keep running if I change tab?
Yes. It's based on your device's clock, so the time stays correct in the background. On phones, keep the screen on, as some browsers pause pages when locked.
Can I save my lap times?
Press Copy lap times and paste them into a spreadsheet, notes app or message. They're copied as tidy columns.
Last reviewed October 2026. Keep this tab open while timing. Phones may pause web pages when the screen locks.