Sleep Calculator
Sleep calculator finds optimal sleep and wake times based on 90-minute sleep cycles. Enter when you want to wake up to find the best times to fall asleep (and vice versa). Accounts for the average 15 minutes it takes to fall asleep.
Sleep Calculator
Best times to fall asleep:
9:15 PM (6 cycles = 9h)Recommended
10:45 PM (5 cycles = 7.5h)
12:15 AM (4 cycles = 6h)
Based on 90-minute sleep cycles. Includes ~15 min to fall asleep.
How to Use Sleep Calculator
- 1Choose wake or sleep mode
- 2Enter your target time
- 3View optimal sleep/wake times
- 4Choose 4–6 sleep cycles
Your Privacy is Protected
Sleep Calculator runs entirely in your browser. Your files and data are never uploaded to any server, never stored, and never shared. Everything happens locally on your device using secure browser APIs.
No server uploadNo account required100% freeWorks on all devices
Frequently Asked Questions
Why are sleep cycles 90 minutes?
A full sleep cycle includes light sleep, deep sleep, and REM stages. Each cycle takes roughly 90 minutes. Waking at cycle end reduces grogginess.
Why Use This Tool?
Files never leave your device
No upload to any server
Instant processing in browser
100% free, no account needed
Tags
sleep calculatorsleep cyclebedtime calculatorwake up timeREM sleep
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