Loading calculators...
Fetching calculator categories and tools for this section.
Preparing tools and content for you. This usually takes a second.
Fetching calculator categories and tools for this section.
Free nap duration calculator: classify a planned nap (power vs mid-length vs cycle) or plan from minutes until you must wake. See sleep inertia risk by band — 20 min = low risk; 26–59 min = high risk in this model.
Last updated: May 25, 2026
Night sleep scheduling? Sleep cycle calculator
How long you expect to actually sleep (timer), not time in bed.
Power-nap range
Lower grogginess risk (model)
This duration often fits mostly lighter sleep stages for adults, which many people find easier to wake from than stopping mid-cycle later on.
Key points
Sleep stages vary by person, age, and sleep debt. Use this as a planning guide—not for diagnosing sleep disorders or replacing medical advice.
Power-nap range
5–25 min power band
Low (model)
vs high risk at 26–59 min
Higher sleep-inertia risk (mid-length)
High inertia risk band
60 min until wake
Mid window: avoid “stopping halfway” if you can
Suggest ~20 min power
120 min until wake
Wide window: power nap or near full-cycle nap
~20 or 90 min options
| Minutes (sleep time) | Zone | Grogginess | Note |
|---|---|---|---|
| 1–4 | Very short nap | low | Limited sleep; usually low inertia |
| 5–25 | Power-nap range | low | Common 10–25 min alertness target |
| 26–59 | Mid-length (higher inertia risk) | high | Often groggier wake than short or ~90 min |
| 60–105 | Long / near one-cycle | moderate | Often discussed with ~90 min anchor |
| 106–480 | Extended nap | moderate | May affect nighttime sleep if late |
Power-nap range · low grogginess risk
This duration often fits mostly lighter sleep stages for adults, which many people find easier to wake from than stopping mid-cycle later on.
Higher sleep-inertia risk (mid-length) · high grogginess risk
This band often overlaps with deeper slow-wave sleep for many adults. Waking from deeper sleep can feel groggy even if the nap felt “helpful.”
Higher sleep-inertia risk (mid-length) · high grogginess risk
This band often overlaps with deeper slow-wave sleep for many adults. Waking from deeper sleep can feel groggy even if the nap felt “helpful.”
Long nap / near one-cycle window · moderate grogginess risk
Longer naps can include more complete cycling through stages for some people. Roughly ~90 minutes is a common rule-of-thumb for “about one cycle,” but real cycles vary.
Short window: favor a brief nap or rest
Mid window: avoid “stopping halfway” if you can
Wide window: power nap or near full-cycle nap
Send the link before setting a timer — especially for the 26–59 minute trap.