Method
The calculator estimates sleep-cycle timing using 90-minute cycles and a short time to fall asleep.
Health / browser tool
Sleep Calculator
Plan around 90-minute sleep-cycle estimates and a 15-minute fall-asleep allowance.
Your inputs stay on your device
Estimate your sleep schedule
live resultEstimated bedtime (4 cycles)
same day
Estimated bedtime (5 cycles)
previous day
Estimated bedtime (6 cycles)
previous day
Sleep-cycle times are estimates based on 90-minute cycles and 15 minutes to fall asleep. They are not medical advice.
Useful context
How it works
Use the calculator first, then scan the details below when you want more context about the inputs, result, or assumptions.
How to use it
Choose bedtime or wake-up mode, enter the known time, and compare suggested cycle-aligned times.
Understand the result
Each suggestion represents a cycle-count estimate, not a guarantee of sleep quality or an exact biological cycle.
Example
Choosing a 07:00 wake-up time can show several suggested bedtimes with different cycle counts.
Notes
Sleep cycles vary between people. Results are estimates and are not medical advice or a substitute for professional care.
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