A stopwatch looks simple: start, stop, reset. But the lap button unlocks much more useful information, especially for running, swimming, cycling and classroom experiments. This guide explains lap times and split times, when to use each, and how to record them with our free Online Stopwatch.
Lap time
A lap time is how long one lap or section took on its own.
Split time
A split time is the total elapsed time from the start to the end of that lap.
Example: 1,600 m run (4 laps of 400 m)
| Lap | Lap time | Split time |
|---|---|---|
| 1 | 1:52 | 1:52 |
| 2 | 1:58 | 3:50 |
| 3 | 2:01 | 5:51 |
| 4 | 1:49 | 7:40 |
Lap times show the runner slowed in laps 2 and 3, then sprinted the last lap. Split times show the overall pace at each point.
How to use the lap button
- Press Start at the beginning.
- Press Lap at the end of each lap; the stopwatch keeps running.
- Press Stop at the finish.
- Copy the lap list to analyse or share.
Keyboard shortcuts make it easier: Space to start or pause, L for lap.
Even pacing
Many coaches recommend an even pace or slightly faster second half (a “negative split”) for longer races. If your first lap is much faster than the rest, you started too quickly.
Converting pace
If you know distance and time, pace = time ÷ distance. A 7:40 time for 1.6 km is about 4:48 per km. Convert distances with the KM to Miles Converter converter.
Classroom and lab uses
Time pendulum swings, reaction times or chemical reactions. Repeating measurements and averaging reduces error.
Accuracy
Browser stopwatches use your device clock and are accurate to around a hundredth of a second. Human reaction time when pressing buttons usually introduces more error than the device itself.
For training plans with the stopwatch, read interval training with a stopwatch. For fixed countdowns, use the Online Timer.
Frequently asked questions
What is the difference between lap time and split time?
Lap time is the duration of one lap; split time is total time from the start.
How accurate is an online stopwatch?
Very accurate; human reaction time is the bigger source of error.
What is a negative split?
Running the second half of a race faster than the first.