A twenty minute timer

This page starts counting 20 minutes the moment it opens, and makes a sound when it finishes. Nothing to set, and nothing to press first.

What people set 20 minutes for

The far end of a safe nap, a HIIT session, a language drill, or twenty minutes of reading before bed.

Worth knowing

Twenty minutes is also the eye-break interval in the 20-20-20 rule: every twenty minutes, look at something twenty feet away for twenty seconds.

Questions

Do the timers keep running if I switch tabs?

Yes. The countdown is measured against a monotonic clock rather than counted in ticks, so a backgrounded tab, a throttled timer or a laptop lid closing does not lose time — when you come back it shows what it should, not what it managed to count.

Does a timer survive a daylight-saving change?

Yes, and the distinction matters. A countdown measures elapsed real time, so a timer set for six hours across a spring-forward still runs six real hours even though the wall clock advances seven. An alarm set for a wall-clock time does the opposite: it fires when the clock says so, which is what you want from an alarm.