Online Stopwatch guide
A big, clean stopwatch for workouts, speeches, cooking, and lab work. Laps show both split and total, and the keyboard does everything so you never hunt for a button.
Why this stopwatch does not drift
A lot of online stopwatches add 10 milliseconds every time a timer fires. That sounds fine until you learn browsers do not promise to fire timers on schedule. Busy pages delay them, and background tabs get throttled to about once per second or slower. Count ticks and you lose time.
This stopwatch never counts ticks. When you press Start it records a reading from performance.now(), the browser's high-resolution monotonic clock. Every time the screen repaints, it subtracts that reading from the current one and shows the difference. If the display freezes for 30 seconds while the tab is hidden, the next repaint still shows the correct total. Monotonic also means it ignores changes to your system clock, so a time sync or a daylight saving shift mid-run does not corrupt the reading.
The display shows hundredths of a second: 1:23.45 means 1 minute, 23 seconds, and 45 hundredths. Past 60 minutes an hours field appears.
Keyboard control
Space starts and stops. L records a lap. R resets. That is the whole list, and it is enough to run a session without looking at the screen, which matters when you are timing a speech rehearsal or holding a plank.
The shortcuts step aside when you do not want them. If your cursor is in a text field, or you are holding Ctrl or Cmd, the stopwatch ignores the key, so typing notes or pressing Cmd+R to reload the page works normally.
Reading lap and total columns
Every lap row shows two numbers. The split is the time since the previous lap. The total is the time since Start. Coaches use the split to see pacing; the total tells you where you are against a goal.
Worked example: a 1-mile run on a 400-meter track is roughly 4 laps. You press L at 1:52.30, 3:47.10, 5:44.90, and 7:38.20. The splits are 1:52.30, 1:54.80, 1:57.80, and 1:53.30. The totals are the times you pressed. The splits show you faded on laps 2 and 3, then kicked on the last one. A total-only stopwatch would hide that.
When you are done, the Copy laps button puts the lap list on your clipboard as plain text, one lap per line. Paste it into a spreadsheet, a training log, or a text to your coach.
The real limit is your thumb
Hundredths on the screen do not mean hundredths of real accuracy. Human reaction to a visual cue takes roughly 0.2 to 0.3 seconds, and that delay hits both the start and the stop. For a 5K or a cooking timer this does not matter. For a 100-meter sprint, where races are decided by hundredths, it does. That is why official track meets use fully automatic timing triggered by the starting gun, not hand-held watches.
Two ways to shrink your error: anticipate the event instead of reacting to it (press as the runner crosses the line, not after), and use the keyboard rather than a mouse, since Space has less travel than moving a pointer to a button.
What people actually time with it
Presentations: a 5-minute lightning talk, with a lap at each section so you can see which part runs long. Interval training: a lap at the end of each work set to check you are holding pace. Studying: a lap per problem to find the question types that eat your time. Lab work: reaction times and titrations where a phone is not allowed at the bench but a laptop is. Cooking: pasta at 9:30, steak rested for 5:00.
If you need to count down to a fixed moment instead, the countdown timer is the better tool. If you already have a start and end time written down and just need the gap, use the time duration calculator.
How we calculate: sources
Frequently asked questions
How accurate is this online stopwatch?
It reads the browser's high-resolution performance.now() clock and displays hundredths of a second. Elapsed time is calculated from that clock, not counted tick by tick, so it does not drift. Your own reaction time (roughly 0.2 to 0.3 seconds) is the bigger error.
What is the difference between a lap time and a split?
Here, the lap (split) column is the time since the previous lap, and the total column is the elapsed time since you pressed Start. A 3-lap run of 1:02.10, 1:01.85, and 0:59.40 shows totals of 1:02.10, 2:03.95, and 3:03.35.
What are the keyboard shortcuts?
Space starts and stops, L records a lap, and R resets. Shortcuts are ignored while you are typing in a text field or holding Ctrl or Cmd, so browser shortcuts still work.
Does the stopwatch keep running if I switch tabs or lock my screen?
Yes. Browsers slow down timers in background tabs, but the elapsed time is recalculated from the clock when you come back, so the reading is still correct.
Can I copy or export my lap times?
Yes. The Copy laps button copies the lap list as plain text, one lap per line, ready to paste into a spreadsheet, notes app, or message.
Can it time more than an hour?
Yes. Hours appear automatically once the time passes 60 minutes, and it keeps counting as long as the tab stays open.
Does the stopwatch run entirely in my browser?
Everything runs in your browser. Nothing you enter is uploaded to a server or stored by us.
Is an online stopwatch accurate enough for sports timing?
For training, yes. The clock itself is precise to well under a millisecond, but hand timing adds roughly 0.2 to 0.3 seconds of reaction error. Official races use automatic timing for that reason.
Does the stopwatch reset if I refresh the page?
Yes. Reloading clears the time and laps, so copy your laps first. The R shortcut ignores Cmd+R and Ctrl+R so you cannot trigger a reset by accident while reloading.