How to use the stopwatch
Press Start to begin and press it again to stop. Resume continues from where you stopped and Reset returns to zero. The display shows minutes, seconds and hundredths, switching to hours:minutes:seconds after an hour.
- Lap: press it while timing to record the time for that segment: a lap of the track, a math problem, a slide in your talk.
- Name: type a name at the top ("400 m run", "Chapter 2") and it is saved with copies and recent sessions.
- Full screen: the button at the top right (F) fills the screen with the digits.
- Shortcuts: Space start/stop, L or Enter lap, R reset, F full screen.
Reading lap and split times
Lap time is the time since the previous lap; Total is the cumulative split from the start. The italic top row is the lap in progress and updates live.
With two or more laps, the fastest lap is tagged green and the slowest red. The vs. prev column shows how much faster (green −) or slower (red +) each lap was than the one before, so you can spot where your pace dropped. The summary shows the lap count and average lap.
Copy, CSV export and recent sessions
- Copy results puts a tidy summary (total, every lap, average, fastest and slowest) on your clipboard for notes or chat.
- Save CSV downloads a spreadsheet-ready file with lap and total times both as 01:23.45 text and as plain seconds for calculations.
- Recent sessions keeps the last 20 sessions every time you reset. Press Restore to bring one back and keep timing.
Why it keeps exact time in background tabs and after a reload
Instead of adding one tick at a time, the stopwatch stores the moment you pressed Start and computes "now minus start". Browsers deliberately slow down scripts in hidden tabs, but this method never drifts: come back to the tab and the time is exact. The display redraws many times per second so the hundredths roll smoothly.
The start time and laps are saved in your browser, so a reload or reopening the page continues the session (time keeps counting while the page is closed). Changing your device clock will shift the result.
Hundredths are displayed, but human button-press timing varies by much more than that, which is why official race timing uses electronic equipment. For training, study sessions and everyday timing it is plenty accurate.
Ideas for study and training
- Track real study time: start when you sit down, stop when you take a break. Name each subject and reset between subjects; each one is kept in recent sessions.
- Time each problem: lap after every question and the slowest one is tagged for review. Use the timer as well when you have a hard time limit.
- Running, swimming, intervals: lap every lap or set to see your average pace and weakest segment.
- Rehearse a talk: lap at each slide to see where the time goes.
- Prefer alternating focus and breaks? The Pomodoro timer cycles 25/5 minutes automatically.
FAQ
Does it keep counting in another tab or when my phone screen is off?
Yes. Elapsed time is computed from the start moment, so even if the browser paused the page, the correct time appears as soon as you return. While running it also asks the browser to keep the screen awake.
Will I lose my time if I reload or close the page?
No. The running time and laps are stored in this browser and continue after a reload. Nothing is sent to a server.
I pressed Reset by accident.
Open Recent sessions and press Restore on the latest entry. The time and laps come back, and Resume continues timing.
Is it accurate to 1/100 of a second?
Time is computed from the device clock in milliseconds and shown to hundredths. Human reaction when pressing the button varies more than that, so it is not a substitute for official race timing.
Can I export laps to Excel or Google Sheets?
Press Save CSV. The file includes formatted times and plain seconds for easy calculations.