Stopwatch tools · Laps & training
Running Split Stopwatch
Know your lap. Find your pace.
Ready when you are
Current lap · 00:00.00
Ready when you are.
Reset this session and remove its recorded marks? Export first if you want to keep them.
Your results
Completed marks appear here. Add a note to remember the details.
A fresh start. Your first mark goes here.
Planning a race goal? Use the running pace calculator to work out your target finish time and print mile or kilometer splits.
How to use the running split stopwatch
Enter the distance covered at each press and an optional target lap time in seconds. Start at your chosen line and record a lap each time you cover that distance. The table compares each cumulative split against an even-paced target.
For a 400-meter track, enter 400 meters. For mile markers, choose miles and enter 1. Pace is calculated from completed marks, not GPS. A negative target difference means ahead; a positive difference means behind. A partial final lap is not included in the recorded distance.
Can I use this as a 400-meter lap timer or mile split timer?
Yes. Change the distance before starting. Target split equals the target seconds per lap multiplied by completed laps. Pause only if you intentionally want to exclude a break; for elapsed race time, leave the watch running.
How accurate is the stopwatch?
The display can show hundredths of a second, but human reaction and browser input latency affect a manual measurement. Live timing uses a monotonic clock, so changing the device time does not change an open session. After a refresh, recovery uses saved device timestamps. Device sleep and a changed clock can affect that recovery. Keep this page and device awake for dependable timing.
Where are my results saved?
Only in this browser on this device, with no account required. Use one tab per tool to avoid overwriting the same saved session. Export CSV before clearing local settings. Each session can hold up to 500 marks and seven days of active elapsed time. Live updates stop while paused; no stopwatch readings are sent to our server.