20 Second Timer
Twenty seconds is the length people actually time by singing something twice at the sink. It is also a third of a minute and the work half of the best known interval pattern. One click starts it.
0:20
Nothing plays until you press start.
The count runs against your device clock, so a tab left in the background still lands on time. The sound is the weak part: a phone that has put itself to sleep may never play it. Do not lean on this, or on any browser timer, where a missed alarm costs you something - medication, an exam, a step in cooking that burns.
The twenty seconds at the sink
This is the length most commonly attached to washing your hands, and the reason everybody knows the trick of humming Happy Birthday twice: the song is there to measure twenty seconds when there is no clock. A timer on the counter does the same job without the singing.
Twenty seconds of work
In interval training twenty seconds is the effort half of the 20-on, 10-off pattern. Eight rounds of twenty plus ten come to 240 seconds, four minutes flat, which is the whole appeal of it. The rest half has its own page, the 10 second timer.
Twenty seconds away from the screen
The common screen-break rule of thumb pairs this page with a long one: every twenty minutes, twenty seconds looking at something far off. Run it against the 20 minute timer and you have both halves.
The arithmetic
Twenty seconds is one third of a minute. Three runs fill a minute and 180 fill an hour.
Before you trust it with something that matters
Other lengths, including the 30 second timer, are listed on the online timer hub.