Stopwatch & Timer
A precise stopwatch with laps and a countdown timer with an alarm — all in your browser.
Track elapsed time with laps or run a countdown with an alarm for workouts, cooking, study blocks and meetings — no app install required.
Who this is for
Anyone who wants a clock running in ten seconds without installing an app: a cook who needs twelve minutes, a student running study blocks, someone timing intervals at the gym, a teacher timing an activity on a projector. Two tools share the page — a stopwatch counting up with laps, and a countdown counting down to an alarm — and you switch between them with the tabs at the top.
How to use the stopwatch
- Press Start. The display runs to hundredths of a second.
- Press Lap to record a split without stopping the clock. Each lap row shows the lap number, the split (time since the previous lap) and the running total.
- Start becomes Pause while running, so you can hold and resume without losing the elapsed time.
- Reset clears the clock and the lap list together.
How to use the countdown
- Type hours, minutes and seconds, or press a preset — 1, 3, 5, 10, 15 or 25 minutes.
- Press Start. The remaining time also appears in the browser tab title, so you can watch it from another tab.
- Pause holds the remaining time and turns into Resume.
- At zero the display shows 00:00, the tab title changes to "Time's up", and the alarm sounds if the sound box is ticked. Stop alarm silences it, and it stops itself after about twelve beeps.
Worked examples
Example 1 — interval training. Start the stopwatch and press Lap at the end of each work interval. The Split column gives you each interval on its own, so you can see the fourth round was eleven seconds slower than the first without doing any subtraction.
Example 2 — a 25-minute study block. Press the 25 min preset and Start. Leave this tab visible on a second screen or beside your work; the countdown in the tab title means you do not need the page in front of you to see how long is left.
Example 3 — cooking. Set 12 minutes, tick the sound box, and press Start. Give the page one click first if the alarm has never sounded on this device — browsers refuse to play audio until you have interacted with the page, so an untouched tab can finish silently.
How the timing actually works
Both tools read a high-resolution monotonic clock rather than counting ticks, so the elapsed and remaining figures do not drift the way a naive interval counter does. The countdown records the moment it should end and compares against it, which means pausing, resuming and slow frames cannot accumulate error.
The display is redrawn on the browser's animation frame. That is what makes it smooth, and it is also the source of the one behaviour worth understanding before you rely on it, described below.
Keep the tab visible if the alarm matters
This is the most important thing to know about any browser timer, including this one. The countdown checks whether it has reached zero as part of redrawing the display, and browsers stop redrawing pages in tabs you are not looking at — that is a deliberate battery-saving measure, not a fault in the page.
The practical consequence: if you switch to another tab or minimise the window, the countdown does not lose track of time, but it may not notice that it finished until you come back. The moment the tab is visible again it catches up instantly and the alarm sounds — just later than it should have. Timing stays correct; the notification is what slips.
So for anything where being told matters — food in the oven, a train to catch — leave this tab on screen. A second monitor, a split window, or simply leaving the browser in front works. If you need an alarm that survives a locked phone or a buried window, use your device's own clock app, which has permission to wake the system in a way a web page does not.
Common mistakes
Backgrounding the tab and expecting a beep. Covered above — it is the single most common disappointment with web timers.
Never clicking the page. Browsers block audio until you interact with a page. Pressing Start counts, so a countdown you started yourself will sound. A page loaded and left untouched may not.
Reloading. Nothing is saved. A refresh clears the stopwatch, the lap list and any running countdown, and there is no recovery.
Expecting the device to stay awake. The page does not hold a wake lock, so a phone that sleeps suspends the timer with everything else until you wake it.
Using laps as race results. Splits are captured when you press the button, so they include your own reaction time — usually a couple of tenths.
Tips
Watch the countdown from another tab. The remaining time is written into the browser tab title, so a narrow strip of tab is enough to keep an eye on it.
Two timers means two tabs. The page runs one stopwatch and one countdown; opening this page in a second tab gives you a completely independent pair.
Press Lap rather than stopping. Pausing and restarting to record a time is unnecessary and loses accuracy — Lap records a split without interrupting the clock.
The 25-minute preset is there for pomodoro-style working blocks. Follow it with the 5-minute preset for the break.
Accessibility notes
The stopwatch and countdown are proper tabs with aria-selected state, so a screen reader announces which one is active, and every control is a real button reachable by Tab. The countdown's remaining time appears in the document title, which means it is available to assistive technology and visible in the tab strip without looking at the page.
Completion is signalled three ways — the display changes, the tab title changes, and the alarm sounds — so it does not depend on hearing alone or on watching the screen alone. The alarm is a plain repeating tone rather than a sudden loud sample. Dark mode is available from the theme toggle.
Limitations (honest)
- The alarm can be late if the tab is not visible. Explained in full above. Elapsed time stays accurate; the alarm waits until the tab is drawn again.
- No notifications and no wake lock. The page cannot raise a system notification or stop your device sleeping.
- Nothing is saved. Reloading or closing the tab clears the stopwatch, the laps and the countdown. There is no history.
- Audio needs a prior interaction because of browser autoplay rules, and will not play through a muted tab.
- Laps include human reaction time. Fine for training, not for official race timing.
- The alarm stops itself after about twelve beeps, so it will not ring indefinitely if you are out of the room.
- Requires JavaScript in a current browser.
Privacy
Both tools are arithmetic on a clock reading, done in your browser. Nothing is sent to our server — not your durations, not your lap times, not the fact that you started a timer — because the page has no endpoint to send them to. The alarm is generated in the browser as a tone rather than downloaded as a sound file, so even that costs no request.
Nothing is stored either, on our side or yours: there is no history and no saved settings, which is why a reload starts you from scratch.
Advertising cookies and your choices about them are described in our Privacy Policy and the consent notice shown on your first visit.
Related tools on ToolsAre.Us
For a deadline days or weeks away rather than minutes, the Countdown counts down to a date and gives you a link you can share with other people. To convert a duration into other units — minutes into seconds, hours into days — use the Unit Converter. If you are coordinating a time across places rather than measuring one, the World Timezones tool handles offsets and daylight saving. The full set is on the home page.
FAQ
Will the alarm go off if I switch to another tab?
Not reliably at the right moment. The countdown checks for zero while redrawing the display, and browsers stop redrawing hidden tabs to save battery. No time is lost — when you return, the page catches up immediately and the alarm sounds — but it sounds late. If being told on time matters, keep this tab visible, or use your device's clock app, which can wake the system in a way a web page cannot.
Why is the alarm silent?
Three usual causes. The sound box is unticked. The tab is muted, either by you or by the browser's site settings. Or the page has never been interacted with — browsers block audio until you click something, so an untouched page can finish in silence. Pressing Start counts as an interaction, so a countdown you started yourself normally sounds.
Can I run two countdowns at once?
Open the page in a second tab. Each tab keeps its own independent stopwatch and countdown. Bear in mind that only the tab you are looking at is being redrawn, so a countdown in a background tab has the delayed-alarm behaviour described above.
What happens if I reload the page?
Everything is lost — the stopwatch reading, the lap list and any running countdown. Nothing is written to storage, so there is no way to recover it. Avoid refreshing mid-session.
Does it keep running if my phone locks?
No. The page does not hold a wake lock, so when the device sleeps the timer suspends along with everything else and resumes when you wake it. For a timer that has to survive a locked phone, use the built-in clock app.
How accurate is the stopwatch?
The clock itself is high-resolution and monotonic, so it does not drift over a session. The practical limit is you: laps are recorded when you press the button, so each split carries your reaction time — typically a couple of tenths of a second. Good for training and cooking, not for official race results.
What do the Lap, Split and Total columns mean?
Lap is the number. Split is the time since the previous lap — the duration of that interval on its own. Total is elapsed time since you started. For interval work, Split is the column you want.
Does it work offline?
Yes, once the page has loaded. Timing and the alarm tone are both generated locally, with no sound file to fetch, so everything keeps working with the network disconnected. The page itself has to be fetched first, and it is not installable as an offline app.
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