Sleep Calculator
Find the best bedtimes for your wake-up time using sleep cycles.
Result
Results are estimates for general information only and are not professional advice.
Sleep cycles
Sleep happens in roughly 90-minute cycles, and waking at the end of a cycle helps you feel more rested. Allowing about 15 minutes to fall asleep, this calculator suggests bedtimes that give you 6, 5 or 4 complete cycles before your alarm.
Frequently Asked Questions
What is the Sleep Calculator?
Find the best bedtimes for your wake-up time using sleep cycles. It runs instantly in your browser and is completely free to use.
What do I need to enter to use the Sleep Calculator?
The Sleep Calculator asks for a single value: Wake-up time. Enter it and the result appears immediately — the calculation runs on your own device, so nothing you type is sent to a server.
How accurate is the Sleep Calculator?
The Sleep Calculator uses standard, widely-accepted formulas, so its figures are reliable estimates for everyday planning. They are not a substitute for advice from a qualified professional.
Is the Sleep Calculator free, and do I need an account?
Yes. The Sleep Calculator — and every other calculator on Calculatis — is completely free, with no registration, no download and no limit on how often you use it.