Sleep Calculators
Bedtime and wake-time planning based on sleep-cycle estimates.
Most used in this category
What these calculators do
Sleep runs in repeating cycles that average about 90 minutes. Waking at the end of a cycle generally feels easier than being pulled out of deep sleep partway through one. These tools count in cycle-length steps and add the time it takes you to fall asleep.
What they are not
They are arithmetic and general information, not medical tools. Ninety minutes is an average — real cycles run roughly 70 to 110 minutes and vary between people and from night to night. Nothing here diagnoses, prevents or treats any condition. Speak to a qualified healthcare professional about persistent sleep problems.
Frequently asked questions
Is this medical advice?
No. These are arithmetic tools giving general information. Speak to a qualified healthcare professional about persistent sleep problems.
Are sleep cycles exactly 90 minutes?
No. Ninety minutes is a commonly used average; real cycles run roughly 70 to 110 minutes and vary between people and from night to night.
How much sleep do adults need?
Generally seven to nine hours. Better cycle timing helps you wake more comfortably within the sleep you get — it does not replace sleep you are missing.