Sleep Calculator
Find the perfect bedtime or wake-up time based on 90-minute sleep cycles.
Sleep cycle timing is approximate and does not replace medical advice.
Sleep calculator
Choose bedtime or wake-up mode and adjust timing estimates.
Many sleep calculators use 90-minute sleep cycles as an estimate.
Add a fall-asleep buffer if you usually take time to fall asleep.
Actual sleep cycles vary between people and throughout the night.
Choose shorter rest, balanced sleep, or longer recovery. Each option updates the suggested bedtime.
Suggested bedtime
11:16 PM
Approximately 5 sleep cycles and 7h 30m of estimated sleep.
Sleep cycles
5
Estimated sleep duration
7h 30m
Fall-asleep buffer
14 min
Uses standard sleep-cycle timing estimates. Reviewed for arithmetic accuracy. Estimate only. Does not replace medical or sleep-specialist advice.
Personalized interpretation
If you want to wake at 7:00 AM, a suggested bedtime is around 11:16 PM after allowing approximately 14 minutes to fall asleep.
This gives approximately 5 sleep cycles and about 7h 30m of estimated sleep.
Some people feel better waking near the end of a sleep cycle, but sleep-cycle timing varies between individuals.
Consistent sleep timing, light exposure, caffeine timing, stress, and sleep quality can affect how rested you feel.
If sleep problems persist, consider speaking with a qualified healthcare professional.
Sleep cycle timeline
Suggested bedtime
11:16 PM
Fall asleep
14 min
Cycle 1
1h 30m
Cycle 2
3h
Cycle 3
4h 30m
Cycle 4
6h
Cycle 5
7h 30m
Wake-up
7:00 AM
Sleep-cycle timing is estimated. Actual cycle length changes across the night and varies between individuals.
What sleep cycles mean
Bedtime vs wake-up calculation
Wake-up mode
Wake-up mode calculates suggested bedtimes based on your desired wake time, sleep-cycle estimate, and fall-asleep buffer.
Bedtime mode
Bedtime mode calculates estimated wake-up windows from bedtime and selected sleep-cycle timing.
Sleep duration by age
Teenagers
Teenagers commonly need more sleep than adults. Individual sleep needs may vary.
Adults
Many adults commonly need around 7–9 hours of sleep. Individual sleep needs may vary.
Older adults
Older adults may experience different sleep patterns and schedules. Individual sleep needs may vary.
Sleep quality factors
Sleep quality may be affected by schedule consistency, stress, light exposure, environment, health conditions, and lifestyle factors.
Limitations and when to seek advice
Sleep-cycle timing is approximate. Total sleep duration and overall sleep quality matter as much as cycle timing.
Sleep calculators cannot diagnose insomnia, sleep apnea, circadian disorders, or other medical conditions.
Shift work, medications, stress, pregnancy, pain, medical conditions, and disrupted schedules can affect sleep timing and quality.
Consider speaking with a qualified healthcare professional if sleep concerns persist or significantly affect daily functioning.
Formula and time explanation
Suggested Bedtime = Desired Wake Time − Fall-Asleep Buffer − (Cycle Length × Number of Cycles)Suggested Wake Time = Bedtime + Fall-Asleep Buffer + (Cycle Length × Number of Cycles)Common default: Sleep Cycle Length ≈ 90 minutesExample 1
Desired wake time: 7:00 AM
Fall-asleep buffer: 15 minutes
5 cycles × 90 minutes = 7.5 hours
Suggested bedtime ≈ 11:15 PM
Example 2
Bedtime: 10:30 PM
Fall-asleep buffer: 20 minutes
5 cycles = 7.5 hours
Suggested wake time ≈ 6:20 AM
Frequently Asked Questions
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