From timing a 5K interval workout to measuring how long a database migration actually takes, a stopwatch is one of the simplest, most universally useful instruments. The lap function adds the crucial ability to capture split times without stopping the clock — essential for training sessions, presentations, and any repeated process you want to compare round by round.
This browser stopwatch starts instantly, records unlimited laps, and runs with centisecond display precision. No app to install, no permissions to grant.
How to Use This Tool
- Click Start to begin timing.
- Click Lap to record a split without interrupting the count.
- Click Stop to pause, Start to resume, Reset to clear.
- Review the lap list to compare each interval.
Frequently Asked Questions
How accurate is a browser stopwatch?
Display updates happen many times a second, and the elapsed time is computed from high-resolution system timestamps, so accumulated error is negligible — a few milliseconds at most, far beyond human reaction-time precision (~150–250 ms).
Does the stopwatch keep running if I switch tabs?
Yes. Even though browsers throttle background tab updates to save battery, the elapsed time is calculated from real timestamps, so when you return the displayed time is correct.
What is the difference between lap time and split time?
Split (cumulative) time is the total since start; lap time is the duration of the segment since the previous lap press. Runners use laps to compare each kilometer; presenters use splits to check total elapsed time against the agenda.