Iona, up for the school pickup
Need to be up at 3:00 pm, 1 cycle
Window 1:30 pm to 3:00 pm. 90 minutes plus a little time to drop off.
Nap Length Calculator
A nap length here is a 90-minute sleep cycle counted back from the time you need to be up. One cycle is 90 minutes. Two cycles are 180. We also leave the idea that falling asleep takes a few minutes. It is a clock tool, not a diagnosis of insomnia and not a shift-work medical plan.
Your details
Enter the time you need to be up and whether you want one cycle or two.
What is this calculator?
A nap length here is a 90-minute sleep cycle counted back from the time you need to be up. One cycle is 90 minutes. Two cycles are 180. We also leave the idea that falling asleep takes a few minutes. It is a clock tool, not a diagnosis of insomnia and not a shift-work medical plan.
How it works
- Enter the clock time you must be awake.
- Choose 1 cycle (90 minutes) or 2 (3 hours).
- Set an alarm for the end time. If you cannot fall asleep, a shorter nap is fine.
Common questions
What is the nap length calculator?
It counts 90-minute blocks back from a wake time so you can see when to lie down.
Why 90 minutes?
Many sleep explainers talk about a cycle near that length. Real sleep is messier. Treat it as a window, not a law.
Will a long nap ruin tonight?
Sometimes, if it runs late. Keep naps earlier if evenings are already hard. The sleep calculator plans the night.
I work nights.
Use the wake time you actually need. This page does not design a night-shift roster.
Example scenarios
Felix, night shift, up at 1:00 pm
Need to be up at 1:00 pm, 1 cycle
Window 11:30 am to 1:00 pm. One cycle before the next stretch.
Colette, two cycles before a 4:30 pm meeting
Need to be up at 4:30 pm, 2 cycles
Window 1:30 pm to 4:30 pm. 180 minutes if she can spare the afternoon.
Understanding your results
If you wake groggy, try one cycle or a 20-minute nap instead. Debt that keeps stacking belongs on the sleep debt calculator, not in a longer afternoon.
About this result
Guidance only. Calculations run in your browser. Numbers are estimates, not a diagnosis.
How we calculate
Need-to-be-up time minus 90 minutes per cycle you choose (1 or 2).
Sources
Limitations
- Cycle length varies.
- Not a diagnosis of a sleep disorder.
- Alarm still required.
When to seek help
See a GP if daytime sleepiness is new, heavy or unsafe, especially when driving.
Spotted an error? Request a correction or read our editorial policy.