Nap Calculator

The right nap length for the right situation.

Not all naps are equal. A 10-minute power nap lifts alertness without grogginess. A 30-minute nap often leaves you feeling worse than before you closed your eyes. A 90-minute nap completes a full sleep cycle and can restore cognitive performance. The difference is which stage of sleep you land in when your alarm goes off. This calculator recommends nap durations based on when you are planning to nap, what you are trying to accomplish, and how long ago you last slept. It distinguishes between three useful nap types: the power nap (10-20 minutes, for alertness), the recovery nap (60 minutes, for memory and cognitive consolidation), and the full-cycle nap (90 minutes, for recovery after short nightly sleep). It will steer you away from the 30-45 minute “nap danger zone,” where you wake mid-deep-sleep and feel foggy for an hour afterward.

The Science

NASA research famously identified 26 minutes as an optimal nap length for pilot alertness. More recent studies refine this: naps under 20 minutes stay in light NREM sleep, producing alertness without grogginess. Naps of 60 minutes enhance memory consolidation but cause some sleep inertia. Naps of 90 minutes cover a full cycle including REM, restoring cognitive performance. The 30-45 minute zone is least recommended because you wake from deep sleep at its worst moment.

How It Works

1

Pick the goal of your nap.

2

Enter how much time you have available.

3

Enter the current time.

4

Get a recommended nap length and wake-up time.

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Frequently Asked Questions

For most people, between 1 PM and 3 PM aligns with the natural post-lunch dip in alertness. Napping after 4 PM risks disrupting your night sleep.
The “coffee nap” trick involves drinking coffee right before a 20-minute nap. Caffeine takes about 20 minutes to kick in, so you wake up just as it hits. Research shows this combination outperforms either alone for post-nap alertness.
Generally avoid naps within 6 hours of bedtime. A 20-minute nap at 3 PM is fine for a 10 PM bedtime; a 90-minute nap at 5 PM likely is not.
Lying quietly with eyes closed still provides some rest. This is sometimes called “quiet wakefulness” and delivers 20-50% of the restorative benefits of a brief nap.
Most children benefit from naps until around age 5. Our Sleep for Kids page covers age-specific guidance.
You are likely napping too long (30-45 minutes) and waking during deep sleep. Try the 20-minute power nap instead - set a hard alarm and resist the urge to snooze.