Online Stopwatch with Laps and Split Times
Start, pause and reset an accurate online stopwatch to the hundredth of a second. Record laps with lap and split times, see the fastest and slowest, and copy them.
Press the space bar to start or pause when no field is selected. Both timers keep running when you switch modes or tabs.
About the Online Stopwatch
The Online Stopwatch counts up from zero to the hundredth of a second. Start, pause and resume as often as you like, record laps while it runs and copy the lap table when you are done. Times under an hour read as minutes, seconds and hundredths, such as 01:05.43; past an hour the hours appear in front, as in 1:02:05.50.
It suits running and swimming laps, circuit training, speed-cubing, timing a presentation rehearsal, a science experiment, a recipe step or how long a task really takes.
How to use the stopwatch
Steps
- Press Start or the space bar when no field is selected.
- Press Lap at the end of each lap. Each press records the time on the clock at that moment.
- Press Pause to stop the clock and Resume to continue from the same time.
- Press Copy laps to copy the table, or Reset to clear the time and every lap.
Reading the lap table
The newest lap is listed first. Lap time is how long that lap took on its own. Split is the total time on the clock when you pressed Lap. Once there are two or more laps of different lengths, the fastest lap is marked in green and the slowest in red.
Lap time and split time
Every lap press stores a split, the clock reading at that moment. The lap time is the difference between that split and the one before it:
For example, laps pressed at 10, 25 and 31 seconds give lap times of 10, 15 and 6 seconds. The third lap is the fastest and the second the slowest, and the splits add up to the total: seconds.
Accuracy
The stopwatch reads a monotonic clock from your browser and works out the elapsed time from the moment you pressed Start, minus any paused time. It never adds up screen refreshes, so it does not drift when the tab is in the background, and the tab title keeps showing the running time. The hundredths are truncated, as on a handheld stopwatch, so 9.999 seconds reads 00:09.99.
Your own reaction time is the largest error in any manual timing. Human reaction times are typically around 0.2 seconds, so for close comparisons use the same person and the same cue each time.
Copying laps
Copy laps places a plain-text table on your clipboard: a header line, then one line per lap with the lap number, the lap time and the split, separated by tab characters. Pasting it into a spreadsheet fills three columns, oldest lap first.
Privacy
Nothing is uploaded; every calculation runs in your browser and never leaves your device. The laps live only on this page and disappear when you close or reload it.
Related tools
Counting down instead of up? Use the Countdown Timer. The Online Timer and Stopwatch page keeps both clocks running side by side, and the Hours Calculator totals the time between two clock times.
Frequently asked questions
What is the difference between lap time and split time?
Lap time is how long a single lap took. Split time is the total time on the stopwatch when you pressed Lap. Laps pressed at 10, 25 and 31 seconds have lap times of 10, 15 and 6 seconds and splits of 10, 25 and 31 seconds.
How precise is the online stopwatch?
It shows hundredths of a second and reads a high-resolution clock from your browser. The hundredths are truncated, as on a handheld stopwatch. In practice your reaction time, typically around 0.2 seconds, is the largest source of error.
Which laps are marked fastest and slowest?
Once you have two or more laps of different lengths, the shortest lap is marked fastest and the longest slowest. With a single lap, or when every lap is equally long, nothing is marked.
How do I copy my lap times?
Press Copy laps. The table goes to your clipboard as text with one line per lap, oldest first, holding the lap number, lap time and split separated by tabs, so it pastes into three spreadsheet columns.
Does the stopwatch keep running if I leave the tab?
Yes. Elapsed time is worked out from the moment you pressed Start, so it stays correct even when the browser slows down a background tab. The tab title shows the running time.
Can I use the keyboard to start and stop it?
Yes. Press the space bar to start or pause when no field is selected. Use the Lap button to record a lap and Reset to clear the time and laps.