Sleep Cycle Calculator
Bedtimes and wake-up times that line up with full sleep cycles.
Times include about 15 minutes to fall asleep. Cycle length varies from person to person.
For information only — not a diagnosis or medical advice. Nothing you enter is sent or stored.
How to use Sleep Cycle Calculator
- Choose whether you want a bedtime for a wake-up time, or wake-up times if you sleep now.
- Enter your wake-up time if needed.
- Click “Calculate” — times marked green give 5–6 full cycles.
Frequently asked questions
Why 90 minutes?
Sleep runs in cycles of roughly 90 minutes. Waking at the end of a cycle, rather than in deep sleep, usually feels easier.
How much sleep do adults need?
Most adults do best with 7–9 hours, which is about 5 to 6 cycles.
Can this replace a doctor?
No. This tool gives general estimates and self-checks for information only. It does not diagnose anything. Please see a qualified health professional for medical advice, and seek urgent care if you feel unwell.
Is Sleep Cycle Calculator free?
Yes. Sleep Cycle Calculator is free to use with no sign-up and no watermark.
Is my information saved or sent anywhere?
No. Everything is calculated in your browser. Nothing you enter is sent to a server or stored.
Does it work on my phone?
Yes. It works in any modern browser on Windows, Mac, Linux, Android and iPhone. Very large files may be slow on older phones.