How do I use the Sleep Calculator?

Choose whether you want to calculate bedtime (when to sleep) or wake time (when to wake up). Enter your target time and the tool calculates optimal times based on 90-minute sleep cycles. Pick a suggested time that gives you 4-6 complete sleep cycles for the best rest quality.

Is the Sleep Calculator free?

Yes, the Sleep Calculator is completely free. It runs entirely in your browser with no signup, no download, and no data sent to any server.

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Sleep Calculator

Calculate optimal bedtime or wake-up time based on 90-minute sleep cycles. Get personalized recommendations for better sleep quality.

sleep calculatorsleep cyclebedtime calculatorwake up timesleep qualityrem cycle

Wake-up Time Minutes to fall asleep

Go to bed at:

Sleep Cycle Info

🌙 One sleep cycle lasts about 90 minutes

💤 Adults need 5-6 cycles (7.5-9 hours) per night

⏱️ Average time to fall asleep: 10-20 minutes

🧠 Waking between cycles helps you feel refreshed

📊 REM sleep increases in later cycles, critical for memory

How to use

How to Use the Sleep Calculator

1 Choose whether you want to calculate bedtime (when to sleep) or wake time (when to wake up).
2 Enter your target time and the tool calculates optimal times based on 90-minute sleep cycles.
3 Pick a suggested time that gives you 4-6 complete sleep cycles for the best rest quality.

Sleep cycles last approximately 90 minutes, moving through light sleep, deep sleep, and REM stages. Waking between cycles (rather than mid-cycle) helps you feel more refreshed and alert.

Most adults need 5-6 complete cycles (7.5-9 hours). The calculator accounts for the average 15-minute fall-asleep time so your wake-up aligns with a cycle boundary.

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