Set minutes and seconds, or tap a preset, and hear an alarm when time is up
Processed in your browser. Nothing is uploaded. Updated on 24 Oct 2026.Pick 1, 2, 3, 5, 10, 15, 30 or 60 minutes, or type any length up to 99 hours, and press Start. The alarm is booked on the sound card clock the moment you press it, so it beeps on time even when you switch to another tab, and the tab title keeps showing the minutes left. Full screen turns the digits into a wall clock for a classroom, a kitchen or a talk.
Tap a preset such as 5 min or 10 min, or type hours, minutes and seconds.
Press Start; the big digits count down and the tab title shows the time left.
When it reaches zero the alarm beeps; press Stop alarm to silence it.
Press +1 min to add time while it runs, or Reset to go back to the length you set.
This stopwatch shows minutes, seconds and hundredths in large digits, with hours added once you pass sixty minutes. Press Lap at the end of each lap or split and the table below records the lap time and the total so far, marking the fastest and slowest once there are three laps. Download CSV saves the table with readable times and exact milliseconds, ready for Excel or Google Sheets.
Browsers slow down timers in a tab you are not looking at, to once a second and in Chrome to once a minute after five minutes. A stopwatch that adds ten milliseconds per tick falls behind as soon as you switch tabs. This one never counts ticks: it notes the clock time when you press Start and works out the elapsed time from the clock every time the screen is drawn. Switch away for an hour and the reading is still exact when you return, and the running time survives a page reload.
Switch to Timer, tap a preset (1, 2, 3, 5, 10, 15, 30 or 60 minutes) or type hours, minutes and seconds, and press Start. The alarm is scheduled on the browser's audio clock at that moment, which keeps time even when the page is hidden. The tab title shows the time left. On an iPhone, iOS 17 and later play the alarm with the silent switch on; older versions mute web sound on silent, and any phone may pause a page that is not on screen.
The rest of the article, and all 6 questions about Online Stopwatch, are on the Online Stopwatch page.
Yes. The stopwatch records the clock time when you press Start and works out the elapsed time from the clock whenever the screen is drawn, rather than counting ticks that a browser slows down in hidden tabs. Switch tabs for an hour, or reload the page, and the reading is still exact to the hundredth of a second.
Switch to Timer, tap a preset from 1 to 60 minutes or type hours, minutes and seconds, then press Start. When the countdown reaches zero the page beeps for 8 seconds and shows Time is up; press Stop alarm to silence it. Press +1 min to add time while the countdown runs.
Safari on iOS 16 and earlier mutes sound from web pages while the ring and silent switch is set to silent; iOS 17 and later play the alarm anyway. An iPhone also pauses a page when the screen locks or another app is in front, so keep the page on screen and use Keep screen on.
No. The stopwatch, laps and timer run entirely in your browser and are stored only in this browser's local storage, so a reload keeps them. Nothing about your times leaves the device; press Reset to clear the laps and the saved state.
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