Nap Calculator
How long should a nap be? For most adults, 10 to 20 minutes. A short nap keeps you in light sleep, so you wake up alert instead of groggy. Got more time? Nap for about 90 minutes: one full sleep cycle.
When should my nap alarm go off?
Enter when you'll lie down and pick a nap length.
Quick reset · 10 min
Alarm at 1:25 PM
Light sleep only. A fast boost in alertness with almost no grogginess.
Recommended
Power nap · 20 min
Alarm at 1:35 PM
The sweet spot for most adults: you wake from light sleep, before deep sleep starts.
Deep-sleep nap · 1 h
Alarm at 2:15 PM
Includes deep sleep, which helps memory, but expect some grogginess right after.
Full-cycle nap · 1 h 30 min
Alarm at 2:45 PM
One complete sleep cycle. You wake from lighter sleep, so grogginess is limited.
Alarm times include 15 minutes to fall asleep. Planning a full night instead? Use the sleep calculator.
How long should a nap be?
It depends on what you want from it. Sleep runs in cycles of about 90 minutes: light sleep first, then deep sleep, then REM. The trick is to wake up during light sleep, either before deep sleep starts or after a full cycle has finished.
| Nap length | What happens | Best for |
|---|---|---|
| 10–20 minutes | Light sleep only | A quick boost in alertness and focus with little or no grogginess |
| 30 minutes | Can slip into deep sleep | Usually avoided: waking from early deep sleep often feels worse |
| 60 minutes | Includes deep sleep | Remembering facts and names, if you can afford some grogginess |
| 90 minutes | One full sleep cycle with REM | Creativity and recovery after a short night, with an easier wake-up |
Tips for a better nap
- Nap in the early afternoon, not in the evening, so it doesn't eat into your night's sleep.
- Always set an alarm. Oversleeping a power nap is how you end up in deep sleep and wake up groggy.
- Make it dark and quiet: an eye mask and earplugs help you fall asleep faster.
- Napping because you're short on sleep every day? A nap helps today, but check your sleep debt too.
More free sleep tools
Sleep Calculator
Best bedtime or wake-up time based on 90-minute sleep cycles.
Sleep Debt Calculator
How much sleep you owe from the past week, and how to pay it back.
REM Sleep Calculator
When each REM period happens and how much REM sleep you get.
Jet Lag Calculator
How long jet lag lasts and how to shift your sleep before you fly.
Sleep Efficiency Calculator
What share of your time in bed you actually spend asleep.
Frequently asked questions
How long should a power nap be?
Between 10 and 20 minutes of actual sleep. That keeps you in light sleep, so you get the alertness boost without the grogginess of waking from deep sleep. Set your alarm for about 20 minutes plus the time it takes you to fall asleep.
Is a 2-hour nap too long?
For most adults, yes. A nap that long often ends partway through a second sleep cycle, which can leave you groggy, and it can make it harder to fall asleep at night. If you need a long nap, aim for one full 90-minute cycle instead.
Why do I feel worse after a nap?
That groggy feeling is sleep inertia. It is strongest when an alarm wakes you from deep sleep, which usually starts around 30 minutes into a nap. Keeping naps under 20 minutes or extending them to a full 90-minute cycle avoids most of it.
When is the best time to take a nap?
Early afternoon, roughly 1 to 3 PM, when most people have a natural dip in alertness. Napping late in the day can push back your bedtime, so leave several hours between a nap and going to bed.
Does this nap calculator work for babies and toddlers?
No. It is designed for adults. Babies and toddlers need much more daytime sleep, and how much depends on their age, so follow your pediatrician's guidance for children's naps.