Sleep Cycle Calculator — Optimal Sleep & Wake Times

Free sleep cycle calculator based on 90-minute cycles. Find the best bedtime or wake-up time — 100% client-side. 100% serverless.

🔒 100% Private
Completely Free
🌐 Runs in Browser
📦 Export Ready

Sleep Cycle Calculator — Optimal Sleep & Wake Times

Tool Workspace

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  1. Choose Mode — Sleep at or wake at.
  2. Set Time — Your target sleep or wake time.
  3. Calculate — See optimal times based on 90-min sleep cycles.

Sleep Cycle Calculator

Calculate optimal sleep and wake times based on 90-minute sleep cycles. Waking between cycles helps you feel more refreshed.

Features

  • Two modes: sleep time or wake time
  • 90-minute cycle calculation
  • 14-minute fall-asleep adjustment
  • 3-6 cycle recommendations

Privacy

All calculations run in your browser.

Frequently Asked Questions

How does it work?

Sleep consists of ~90 min cycles. Waking between cycles (not during) leaves you feeling refreshed. 14 min is added for falling asleep.

How many cycles are ideal?

5-6 cycles (7.5-9 hours) is optimal for most adults.

Is my data safe?

Yes. 100% in your browser.