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Sleep Calculator
Wake up refreshed — bedtimes and wake times aligned with 90-minute sleep cycles.
Enter a time to see your sleep-cycle options.
Formula
Wake time = bedtime + (5–6 × 90-minute cycles) + ~15 minutes to fall asleep
How to calculate
- 1Start from your bedtime and add about 15 minutes to fall asleep.
- 2Add 90 minutes per full sleep cycle you want.
- 3Five cycles (7.5 hours) or six cycles (9 hours) end in a light stage.
- 4To wake at a set time, subtract the cycles and 15 minutes instead.
How to use this calculator
- 1Enter the time you need to wake up, or the time you plan to sleep.
- 2Choose 5 or 6 cycles for your schedule.
- 3See the ideal bedtimes or wake times for each cycle count.
- 4Pick the option that fits your evening and stay consistent daily.
Examples
Wake at 6:30
For six cycles, fall asleep by 9:15 pm; for five, 10:45 pm — lights out 15 minutes earlier.
Bed at 11 pm
Waking after five cycles lands near 6:30 am; six cycles lands near 8:00 am.
Common questions
Is 90 minutes per cycle exact?
It is the average — individual cycles run 80–110 minutes. Treat results as targets and refine with how you feel on waking.
Why wake at the end of a cycle?
Waking in a light sleep stage feels easier; mid-deep-sleep alarms cause the groggy feeling called sleep inertia.
How much sleep do adults need?
Most adults need 7–9 hours — five to six full cycles covers that range.
