Nap Length Calculator
Pick a nap length that avoids grogginess.
Enter your values
ⓘ Live results
Results
- Set your alarm for
- 28 minutes from now
- Actual sleep
- 20 min
- Grogginess risk
- Low
- Latest recommended nap time
- Before 3 pm to protect night sleep
Quick answer
Naps of 10-20 minutes boost alertness without grogginess; 90 minutes completes a full cycle and aids memory.
end time = start + nap length + fall-asleep time
How to use the Nap Length Calculator
- 1Choose the outcome you want from the nap.
- 2Add the minutes you need to drop off.
- 3Set the alarm for the combined total.
Worked example
Using the values the calculator loads with:
Inputs
- Nap goalPower nap (20 min)
- Time to fall asleep8 min
Results
- Set your alarm for28 minutes from now
- Actual sleep20 min
- Grogginess riskLow
- Latest recommended nap timeBefore 3 pm to protect night sleep
Frequently asked questions
Why do 30-60 minute naps feel bad?
You wake from deep slow-wave sleep, which causes sleep inertia for up to 30 minutes.
Does a coffee nap work?
Drinking coffee immediately before a 20-minute nap times the caffeine peak with waking.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.