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Sleep Calculator

Find perfect sleep and wake times. This tool runs 100% locally in your browser.

Medical Disclaimer: This tool is provided for informational and educational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

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Sleep Quality Optimizer

I want to wake up at...

To wake up feeling refreshed, you should try to sleep during 90-minute cycles. Waking up between cycles prevents grogginess.

6 Cycles (9h)
09:45 PM
Bedtime
5 Cycles (7.5h)
11:15 PM
Recommended
4 Cycles (6h)
12:45 AM
Bedtime
3 Cycles (4.5h)
02:15 AM
Bedtime
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What is Sleep Calculator?

Wake up feeling refreshed! This calculator works backwards from your wake time (or forwards from bedtime) to find the best times to sleep based on 90-minute sleep cycles. Waking up in the middle of a deep sleep cycle causes grogginess.

When to Use This Tool

  • 1Improving morning energy
  • 2Planning bedtime
  • 3Avoiding sleep inertia

Examples

Input
Wake up at 7:00 AM
Result
Sleep at: 10:00 PM or 11:30 PM

Frequently Asked Questions

Why 90 minutes?

The average human sleep cycle takes about 90 minutes to move through Light, Deep, and REM sleep phases.

Privacy & Security

Privacy is our priority. Unlike many other online tools, ToolsHub doesn't upload your data to any server. Whether you're processing sensitive text, calculating financial data, or generating passwords, everything stays in your browser.