Sleep Calculator
Find the best bedtime or wake-up time using 90-minute sleep cycles.
- Runs in your browser
- No upload on server
- Free, forever
- Enter values
- See result
- Copy or share
I want to…
How it works
You sleep in cycles of about 90 minutes. Waking at the end of a cycle feels far better than in the middle of one. We also add 14 minutes for falling asleep.
Go to bed at
90-min cycles- Recommended9:46 PM6 cycles · 9 hours of sleep
- Recommended11:16 PM5 cycles · 7.5 hours of sleep
- 12:46 AM4 cycles · 6 hours of sleep
- 2:16 AM3 cycles · 4.5 hours of sleep
How this works — and why it's private
- Pick whether you want to set a wake-up time or a bedtime.
- Enter the time — we account for the ~14 minutes it takes to fall asleep.
- Choose a time that ends after 5 or 6 full cycles to wake up refreshed.
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