Online Timer & Stopwatch

Using the countdown timer

1. Choose a length. Either tap one of the six presets (1, 5, 10, 15, 25 or 60 minutes) or fill in the hours, minutes and seconds boxes. The big display updates as you type.
2. Press Start. The button turns into Pause, and the remaining time is also written into the browser tab title, so you can read it from another tab.
3. Press Pause to freeze the countdown with the remainder kept, then Start again to continue from that point.
4. Press Reset to stop and return the display to whatever the three boxes currently say. Use Full screen to enlarge the clock for a classroom or a stage.

When the count reaches zero the display shows 00:00, the title changes to "Time is up!" and a short alarm plays: six beeps of 880 Hz, each about a quarter of a second long, spaced half a second apart.

How the timing works

The timer does not simply subtract one every second. When you press Start it records the exact clock time at which the countdown should finish, then checks the system clock five times a second and displays the difference. This matters because browsers slow down or pause timers in background tabs. A timer that counted its own ticks would drift or stall, whereas one that compares against the clock is right the moment you look at it again.

The display rounds seconds upward. With 4.2 seconds remaining you see 00:05, and the clock reads 00:00 only when the time has truly run out. The hours part is hidden until there is at least an hour left, so a 90-minute timer starts as 01:30:00 and drops to 59:59 an hour later.

Because the end time is based on the device clock, a manual clock change or a sleeping laptop will move the finish time. If your computer goes to sleep during a long countdown, check the display when it wakes.

The stopwatch

Switch to Stopwatch for the opposite job. It counts up in minutes, seconds and hundredths, shown as 00:00.00. Start and Stop pause and resume the same run, and the minutes keep growing past 60 rather than rolling into hours.

Lap records a line without stopping the clock. Each line shows the total elapsed time and, in brackets, the split since the previous lap. For example, laps at 01:05.20 and 02:10.70 are listed as "02:10.70 (+01:05.50)" for the second one. The newest lap appears at the top. A lap pressed while the display still reads zero is ignored, and Reset clears the clock and the list together.

Common uses

• Focused work: run 25-minute blocks followed by a break, or use the 60-minute preset for a longer session.
• Cooking and tea: set a custom value such as 3 minutes 30 seconds without leaving the page.
• Presentations and exams: put the timer in full-screen mode so the room can see how long is left.
• Workouts and training: use laps to compare intervals, sprints or practice speeches, since the split shows exactly how each round differed.

Tips and limits

• Changing the hour, minute or second boxes while the timer is running has no effect on the current countdown. Press Reset and then Start to use the new values.
• Pressing a preset button also stops any running countdown and loads that length immediately.
• Browsers may mute audio from tabs you have not interacted with, and the device's volume or silent switch still applies. Test the sound once with a short countdown such as 5 seconds before relying on it.
• Keep the tab open. If you close it, the countdown is lost, because nothing is stored.
• If sound is unreliable, the tab title change gives a second signal, and the full-screen clock is easy to spot from across a room.

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