Twenty minutes is a well-known "power nap" length — long enough to feel rested without dropping into deep sleep, which is why sleep researchers commonly recommend it. It's also a common baking duration and a solid study block length when paired with a short break after. The timer opens set to 20 minutes.

For naps especially, a countdown you can trust to actually go off — even if your phone locks or the browser tab isn't in focus — matters more than almost any other use case. This timer recalculates the exact remaining time from a stored end point rather than a number that can silently drift while your device is asleep, so the alarm still fires on time.