Nap calculator
Tell it when your nap starts and it tells you when to set your alarm, for a quick 20-minute power nap or a full 90-minute cycle.
- Free, no sign-up
- Power naps and full cycles
- Allows time to drop off
- Made in your browser
Planning a full night’s sleep instead? Use the sleep calculator
A nap of 10 to 20 minutes usually ends before deep sleep. A 90-minute nap is a full cycle. Naps of 30 to 60 minutes are more likely to end in deep sleep, which can leave you groggy.
Starting a nap at 14:00? Set an alarm for:
- 14:1510 min asleepQuick rest
- 14:2520 min asleepPower nap
- 15:3590 min asleepFull cycle
Napping late in the afternoon or evening can make it harder to fall asleep at night.
How the nap calculator works
It adds the time it takes you to fall asleep to your start time, then the length of the nap. It offers three lengths:
- 10 minutes: a quick rest when you’re short of time.
- 20 minutes: the classic power nap. Long enough to help, and usually over before deep sleep starts.
- 90 minutes: a full sleep cycle, ending in lighter sleep.
Getting the most from a nap
- Set an alarm. A 20-minute nap easily turns into two hours without one.
- Nap earlier in the day. Early afternoon is easiest to fit around your night’s sleep.
- Make it dark and quiet. An eye mask or earplugs help you drop off faster.
- Give yourself a minute. Feeling a bit slow straight after waking is normal and soon passes.
Planning a full night instead? The sleep calculator works out bedtimes and wake-up times in 90-minute cycles. For heavy sleepers, see our guide to waking up if you sleep through alarms.
This calculator is a general guide to timing, not medical advice. If you regularly need naps to get through the day, talk to a GP or doctor.
Frequently asked questions
How long should a nap be?
Many people find 10 to 20 minutes works best for a quick boost, because it usually ends before deep sleep. If you have time, a full 90-minute cycle is the other common choice. Everyone is a little different, so try both.
Why do I feel worse after some naps?
Being woken during deep sleep often leaves people groggy for a while. Naps of around 30 to 60 minutes are the most likely to end there, which is why this calculator skips them.
Why does it add time to fall asleep?
Your nap only starts once you’re asleep, not when you lie down. It adds 5 minutes unless you change it.
When is the best time to nap?
Early afternoon suits most people. Napping late in the afternoon or evening can make it harder to fall asleep at night.
Is this medical advice?
No. It’s a general guide to timing only. If you regularly need naps to get through the day, talk to a GP or doctor.