Online stopwatch and timer

What this stopwatch and timer does

This tool bundles two clocks into one screen. The stopwatch counts up from zero, so you can measure how long something takes: a workout set, a phone call, a lap on the track, or how fast you finish a task. The timer does the opposite — it starts from a time you choose and counts down to zero, where it fires an alarm. That is the classic kitchen, study or break reminder.

Everything runs inside your browser. No account, no install, no data leaving your device: close the tab and the clock leaves with you.

Using the stopwatch

1. Open the Stopwatch tab and press Start. The clock begins at 00:00.00.
2. While it runs, press Lap to save the current time without stopping. Each lap shows its split (how long that segment took) and the running total.
3. Use Pause to freeze the number and Resume to keep going from where you were.
4. Reset sends everything back to zero and clears the laps.

Using the timer

1. Switch to the Timer tab and type the minutes and seconds, or tap a preset (1, 3, 5 or 10 minutes).
2. Press Start and watch the live countdown.
3. When it hits zero the box turns red, flashes, and a short three-beep alert sounds. You can mute it with the sound button before you begin.
4. Pause halts the count and Reset returns it to the original value.

Why the timing stays accurate

Many sloppy stopwatches add up “ticks” — for example, “+10 ms every 10 ms”. The trouble is that browsers do not fire those callbacks with perfect precision, so the error piles up and after an hour the clock runs slow. This tool uses a different method: it records the real start instant with Date.now() and, on every screen refresh, measures the gap to the current instant. The reading never drifts, even if the browser gets busy.

Time is shown in hundredths of a second. Converting from milliseconds is direct:

Once you pass one hour, the tool automatically adds the hours field in front.

Example

You are running four laps of a track. You start the stopwatch as you set off and press Lap each time you cross the line. When you finish you see something like this:

• Lap 1 — split 01:02.40, total 01:02.40
• Lap 2 — split 00:59.80, total 02:02.20
• Lap 3 — split 01:01.10, total 03:03.30
• Lap 4 — split 00:58.90, total 04:02.20

At a glance you know your fastest lap was the fourth (58.9 s) and the whole run took just over four minutes.

Frequently asked questions

Does it keep counting if I switch tabs or lock my phone?

The stopwatch never loses real time because it is based on the system clock, so you will see the correct value when you return. That said, while the tab is in the background the browser may stop refreshing the screen; the numbers “jump” when you come back, but the total is exact. On the timer, the sound alert can be delayed until the tab is active again.

Why doesn’t the alarm sound?

Browsers only allow audio to play after you interact with the page, which is why the sound is prepared when you press Start. If you still hear nothing, check that the button reads “Sound on” and that your device volume is not muted.

How many laps can I record?

As many as you need; the list grows downward and the newest lap appears on top. There is no practical limit for normal use.

Can I set a timer longer than an hour?

Yes. The minutes field accepts up to 180 (three hours). If you need to count whole days, a countdown to a specific date is more convenient than this timer.

Are my times saved if I reload?

No. The tool is deliberately ephemeral: on reload or close, the stopwatch, its laps and the timer all return to zero.