Chronira
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Online stopwatch

This online stopwatch times anything to the hundredth of a second, records lap and split times, and can beep you into the start or chime at regular intervals. It keeps counting exactly in a background tab and even after a page reload.

00:00.00

Ready

Counts down with beeps, then starts on a long tone: handy for races and drills.

Chimes each time the stopwatch passes the interval, without stopping it.

Keyboard: Space starts and stops, L records a lap, R resets.

The stopwatch keeps running if you reload; it is saved only in this browser.

How to use the stopwatch

Press Start to begin. The same button becomes Stop, and then Resume if you want to carry on from where you stopped. While it runs, Lap records a split; when it is stopped, Reset clears the time and the laps. The display shows minutes, seconds and hundredths, and adds hours automatically after 59:59.99.

Everything you do is saved in this browser, so a running stopwatch survives an accidental reload or a closed tab: open the page again and it is still counting.

Start alerts and alarm sounds

A start alert counts you in with short beeps and starts the clock on a long tone. It is the online equivalent of “ready, set, go” and keeps your hands free at the start of a sprint, a plank or a speech.

An alarm sound at a fixed interval turns the stopwatch into a simple interval trainer. Set it to every minute for EMOM workouts, every 5 minutes to pace a long run, or every 15 minutes to remind you to take a break during focused work. The stopwatch keeps counting through each chime.

Stopwatch or timer?

A stopwatch counts up from zero and tells you how long something took. To count down a fixed length and get an alarm when it ends, use the online timer, which can also run several named timers at once. For work and study sessions with breaks, the pomodoro timer alternates focus and rest automatically.

Good to know

  • Browsers only allow sound after you interact with the page, so the alert and alarm sounds are prepared when you press Start.
  • Lap times are kept to the hundredth of a second; your device’s clock is the reference.
  • Nothing you time is sent to a server: the stopwatch runs entirely on your device and works offline.

Frequently asked questions

How do I record lap times?

Press Lap (or the L key) while the stopwatch is running. Each lap appears in the table with its own time and the running total; the fastest lap is shown in green and the slowest in red once you have two or more. Copy laps puts the whole table on your clipboard, ready to paste into a spreadsheet.

What does the start alert do?

Choose a 3, 5 or 10-second countdown under Start alert. When you press Start, the stopwatch beeps once per second and then starts on a long, higher tone, so you can put your phone down and get ready, like a starter's signal for a race or an interval drill.

Can the stopwatch play an alarm sound?

Yes. Pick an interval under Alarm sound, for example every 5 minutes, and the stopwatch chimes each time that much time has passed, without stopping. Phones that support it also vibrate. Turn the sound off with the Alarm sound button; your choice is remembered.

Is the stopwatch accurate if I switch tabs?

Yes. Elapsed time is calculated from the moment you pressed Start, using your device's clock, rather than by counting ticks. Background tabs, a locked screen or even a reload do not make it drift: the time shown when you come back is exact.

Are there keyboard shortcuts?

Space starts and stops the stopwatch, L records a lap and R resets it when stopped. Full screen shows only the large digits, which is useful on a projector or a tablet at the side of a track.

Calculated with Chronira · https://chronira.com/stopwatch/

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