Sleep Cycle Calculator
Find the best times to wake up based on when you go to bed, using 90-minute sleep cycles.
- Free to use
- Accurate results
- No registration required
- Works on all devices
Your result
06:45
5 cycles (7.5 hours)
AI explanation
Formula
Wake-up time = bedtime + minutes to fall asleep + (90 minutes × number of sleep cycles)Worked example
Bedtime 23:00, 15 minutes to fall asleep
| Field | Value |
|---|---|
| Bedtime (24-hour) | 23:00 |
| Minutes to fall asleep | 15 |
| 5 cycles (7.5 hours) | 06:45 |
Assumptions
- Assumes an average sleep cycle length of 90 minutes, a commonly cited approximation — actual individual cycle length varies.
- Waking at the end of a full cycle (rather than mid-cycle) is associated with feeling more rested, but individual results vary.
- Informational only — not personalized medical advice, and not a substitute for treatment of a diagnosed sleep disorder.
Frequently asked questions
How does this differ from the Sleep Calculator?
This calculator works forward from a bedtime to suggest wake-up times; the Sleep Calculator works backward from a wake-up time to suggest bedtimes. Both use the same 90-minute cycle math.
Why does waking at the end of a cycle matter?
Sleep cycles move through lighter and deeper stages; waking during deep sleep (mid-cycle) often feels groggier than waking at a natural cycle boundary, when sleep is lighter.
How many sleep cycles should I aim for?
Most adults do best with 5-6 complete 90-minute cycles (7.5-9 hours), though individual sleep needs vary — this calculator shows several options to choose from.
Related calculators
Sources
- Principles and Practice of Sleep Medicine — American Academy of Sleep Medicine. Effective 01-01-2017, reviewed 13-09-2026.
This calculator provides a general estimate only and does not constitute personalized medical advice. If you have ongoing sleep difficulties, consult a healthcare professional.
Report a calculation issue