20 minute timer
What a 20-minute timer is good for
- Screen breaks. The College of Optometrists recommends the 20:20:20 rule: every 20 minutes, look at something about 20 feet (6 metres) away for about 20 seconds. Run this timer while you work and press Start again after each break.
- Revision blocks. Twenty minutes on one topic, then a short self-test, keeps revision active.
- Activity for disabled children. NHS guidance says disabled children and young people should aim for 20 minutes of physical activity a day, split into smaller chunks if needed.
- A short nap. Set the alarm before you lie down so a rest doesn't turn into an afternoon asleep.
- Reading or practice. Twenty minutes a day of reading with a child or practising an instrument is easy to fit in and to keep up.
- One-to-one meetings. Twenty minutes is enough for a weekly check-in without it filling the afternoon.
How it works
Press Start and the 20-minute countdown begins; the bar and the browser tab show the time left. The timer counts to a fixed end time, so it stays accurate if you switch tabs, and an alarm sounds at zero while the numbers flash. Full screen makes the digits readable from across a room. Space starts and pauses, R resets. To share a different length, add ?t= and a number of seconds to the address: datetime.uk/timer/?t=1500 opens a 25-minute timer.
For focus sessions with breaks built in, use the Pomodoro timer. For any other length, use the online timer.
Frequently asked questions
What is the 20-20-20 rule?
Every 20 minutes, look at something about 20 feet away for about 20 seconds. The College of Optometrists recommends it as a reminder to take short breaks from a screen.
Will the timer keep going if I switch tabs?
Yes. It counts to a fixed end time and the alarm is scheduled in advance, so it stays accurate in a background tab. Closing the tab stops it.
How do I restart it after each break?
When the alarm sounds, press Start again or press Space. The timer runs another 20 minutes.