Stopwatch

How to use the stopwatch

Click "Start" to begin timing. Click "Lap" at any point to record a split time without stopping the clock. Click "Start" again (now labeled "Stop") to pause, and "Reset" to clear everything and start over.

How lap timing works

Each lap shows two numbers: the split (time since the previous lap) and the cumulative total (time since you hit Start). That combination is what a runner needs to see mile splits, what a swim coach needs to time each length, and what a home cook needs to check "how long has this been resting" without losing track of the overall cook time.

Stopwatch vs. countdown timer

A stopwatch counts up from zero with no end point use it when you don't know in advance how long something will take, like a workout set, a public-speaking rehearsal, or a science experiment. A countdown timer counts down to zero from a time you set use it when you already know the duration, like a 20-minute presentation slot or a 10-minute egg boil. If you need the countdown version, see our Countdown Timer.

Does it stay accurate in a background tab?

Yes, with one caveat. This stopwatch calculates elapsed time by comparing the current timestamp to the moment you clicked Start, rather than simply counting up a number every tick. That means the value it shows is always mathematically correct even if your browser throttles background tabs and updates the display less often while you're on another tab. When you switch back, the display catches up to the correct elapsed time instantly it never loses or gains time, it just may not visibly update every 10 milliseconds while hidden.

How precise is browser-based timing?

This stopwatch updates its display every 10 milliseconds and reads from your device's system clock, which is precise enough for virtually every everyday use interval training, cooking, board game turns, and reaction-time games. It isn't a certified competition timer (Olympic-level track and swimming events use dedicated hardware accurate to thousandths of a second), but for personal and casual use, the accuracy is effectively indistinguishable.

FAQ

How accurate is this stopwatch?
It updates every 10 milliseconds using your browser's system clock, accurate enough for workouts, cooking, games, and everyday timing.

Does it keep running if I switch tabs?
Yes the stopwatch is based on actual elapsed time, not a visual animation, so it stays accurate even if the tab is in the background.

Can I record more than one lap?
Yes there's no limit to the number of laps you can record in a session. Each one appears in the list with its split time and cumulative total, with the most recent lap at the top.

What's the difference between a lap time and a split time?
They're often used interchangeably, but strictly, a "split" is the time since the previous lap, and a "lap time" can mean either that or the total elapsed time at that point. This tool shows both numbers side by side so there's no ambiguity.

Can I use this for interval training?
Yes, though for structured work/rest intervals (like 30 seconds on, 15 seconds off) a countdown timer is usually easier since it can alert you automatically the stopwatch is better suited to open-ended timing where you're recording splits manually.

Does resetting clear my lap history?
Yes clicking Reset clears the clock back to zero and removes all recorded laps. There's no way to recover them afterward, so note down any times you need before resetting.