A stopwatch online, accurate to the hundredth
This stopwatch measures elapsed time from your browser's high resolution clock and shows it in minutes, seconds and hundredths, with hours once you pass the hour. It does not add up ticks, which browsers slow down in background tabs. It compares the current time with the moment you pressed Start, so it stays right when you switch tabs, and it even continues after a reload because the start time is saved in your browser.
Lap times and split times
Every time you press Lap, the stopwatch records two numbers. The lap time is how long that lap took on its own, measured from the previous lap. The split time, shown as the total, is the time from the start up to that moment. Runners use lap times to check that each lap is even and split times to see whether they are on track for a target.
The fastest lap is marked in green and the slowest in red as soon as you have two laps or more, so you see at a glance where you lost time.
How to use the stopwatch
- 1Press Start or the Space bar. The time runs until you press Stop, and Start again continues from there.
- 2Press Lap or the L key at the end of each lap, round or task. The table shows the lap time and the total for each one.
- 3Copy the laps as text or download them as a CSV file. Reset, or the R key, sets the stopwatch back to zero.
Typical uses
- Running and swimming: lap times on a track or in a pool, and splits for each kilometer or mile.
- Talks and presentations: time each section of a rehearsal and see which part runs long.
- Work and study: measure how long tasks really take, or time each step of an experiment.
- Games and cooking: time turns, rounds or a recipe step, in full screen so everyone can see it.
Frequently asked questions
How accurate is this online stopwatch?
The time comes from your browser's high resolution clock, which measures in fractions of a millisecond. The display shows hundredths of a second. What limits accuracy in practice is your reaction time when you press a key or a button, which is usually around 0.15 to 0.25 seconds.
What is the difference between a lap time and a split time?
A lap time is how long one lap took on its own, from the previous press of Lap to this one. A split time is the total time from the start up to that press. The table shows both, so you see how even your laps were and where you stood overall.
Does the stopwatch keep running if I reload or close the tab?
Yes. The start time and your laps are saved in this browser, so a reload or a closed tab continues where it was, and a running stopwatch keeps counting in the meantime. Press Reset to clear it. Nothing is sent to a server.
Does it work in a background tab?
Yes. Browsers slow down pages you are not looking at, but the stopwatch does not count ticks. It compares the current time with the moment you pressed Start, so the elapsed time is right as soon as you come back.
How do I save my lap times?
Press Copy laps to get a plain text list you can paste into a message or a note, or Download CSV for a file that opens in Excel, Numbers or Google Sheets. The CSV also has the times in seconds, ready for averages and charts.