How a lap timer works
A lap timer is a stopwatch that keeps running while you mark the end of each circuit. Every press stores the moment it happened; the lap time is the gap since the previous press and the split is the total since the start. Nothing is lost between presses, so the laps always add up exactly to the total.
The lap table marks each lap faster (green) or slower (amber) than the previous one and than your average. The strip above it scales every segment to its duration: a slow lap is visibly wider. Save the session to history to compare it with next week's.
Lap timing by sport
| Activity | Where to press | Tip |
|---|---|---|
| Running track (400 m) | As the torso crosses the start/finish line | Stand level with the line so you see the crossing, not an angle |
| Swimming | On the wall touch at your end | For 50 m laps in a 25 m pool, press every second touch |
| Karting / RC cars | As the nose passes a fixed marker | Pick a marker on a straight where the car is easy to see |
| Cycling (velodrome, loop) | As the front wheel passes the line | Use full screen so a rider can read it from the track |
| Production / time study | At the same step of each cycle | Use the CSV export to work out average cycle time |
To time several athletes at once, switch to multiple stopwatches. To race against a target time per lap, use the split timer, and plan the lap times with the pace calculator.
Questions people ask
What does lap mean on a timer?
Pressing Lap records the time of the segment just finished while the stopwatch keeps running. The lap time is the duration since the previous lap press; the split is the total time since the start.
What is the difference between a lap timer and a split timer?
They use the same presses. A lap timer focuses on each segment's duration; a split timer focuses on cumulative time at each checkpoint, often compared against a target. This page shows both, and our split timer adds ahead/behind against a goal.
How many laps can I record?
There is no practical limit. Laps are kept in your browser and can be copied, exported to CSV or saved to history.
Can I use this lap timer on a phone?
Yes. The Start, Lap and Reset buttons are large thumb targets, the screen layout fits phones, and timing continues correctly if the screen locks.
Is a phone or web lap timer accurate enough for a track day?
For hand timing, yes: the clock is far more precise than your press, which adds about 0.1 to 0.3 s. Motorsport events that need hundredths use transponders or GPS lap timers that trigger automatically.