Sleep Calculator
Find the perfect bedtime or wake-up time based on 90-minute sleep cycles. Wake up refreshed, not groggy.
What time do you want to wake up?
Why 90-minute cycles?
During sleep your brain moves through cycles of light sleep, deep sleep, and REM sleep. Each cycle takes about 90 minutes. Waking at the end of a cycle — not in the middle — is why you feel refreshed instead of groggy.
How much sleep do you need?
- Teens (14–17): 8–10 hours
- Adults (18–64): 7–9 hours
- Seniors (65+): 7–8 hours
🔒 All data stays private on your device only.
How to use
Pick your mode
Choose whether you want to wake up at a set time or fall asleep right now.
Set the time
Enter your wake-up time, or let us use the current time to plan your night.
Follow the best option
Pick a bedtime or wake time aligned with complete 90-minute sleep cycles.
Why sleep cycles matter
- 🌿Wake up at the end of a sleep cycle so you feel refreshed, not groggy.
- 🌿See six bedtime options ranked from best to avoid.
- 🌿Accounts for the 14 minutes it takes on average to fall asleep.
- 🌿Plan backwards from your alarm or forwards from right now.
- 🌿100% private — nothing leaves your device.
- 🌿No signup, works on any phone or laptop.
Frequently asked questions
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