Sleep Calculator
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Sleep Calculator
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How it works
About this calculator
Choose a wake-up time to see the bedtimes that fit four, five or six complete sleep cycles — or start from now and see when you would wake up. A 15-minute buffer for falling asleep is included.
Why 90 minutes?
A typical sleep cycle runs about 90 minutes. Waking at the end of a cycle usually feels easier than waking mid-cycle.
Fifteen minutes to settle
The calculator reserves 15 minutes to fall asleep before the first cycle begins.
A planning aid
Sleep needs vary. If you are consistently tired, talk to a clinician rather than optimising numbers.
Questions & answers
Frequently asked
How many cycles should I aim for?
Most adults do well with five or six cycles, roughly 7.5 to 9 hours. Four cycles suits shorter nights.
Does it account for waking up during the night?
No. It is a simple cycle estimate; interruptions, caffeine and screen light all affect real sleep.
Results are provided for convenience. For legal, payroll or medical decisions, confirm with a qualified professional.