Sleep Calculator
Find the best times to sleep or wake up based on 90-minute sleep cycles — so you wake up refreshed, not groggy.
Go to sleep at one of these times to wake up refreshed between sleep cycles:
Based on ~90-minute sleep cycles + ~15 min to fall asleep. A general guide, not medical advice.
Processed 100% in your browser — nothing you enter here is ever uploaded.
Common use cases
Wake up refreshed
Find bedtimes that let you wake at the end of a cycle, not mid-cycle (which feels groggy).
Plan an early start
Have to be up early? See exactly when to sleep.
Quick nap / sleep now
Tap Now to see the best wake-up times from this moment.
How to use the Sleep Calculator
Choose whether you want to set a wake-up time or a sleep time.
Pick the time (or tap Now).
See the best matching times — each is a whole number of ~90-minute sleep cycles so you wake between cycles.
Pick a time that also gives you enough total sleep for the day.