Sleep calculator
Find when to sleep or wake up based on 90-minute sleep cycles.
Our sleep calculator computes instantly as you type and shows every intermediate result so you understand the math. Free, no sign-up, works on any device.
Sleep calculator: how to use it
- Enter your values (you can switch units).
- The result is calculated automatically.
- Review the breakdown and results table.
- Copy the result in one click.
Features
- Real-time calculation.
- Detailed breakdown and tables.
- Metric and imperial units.
- Private: nothing leaves your browser.
Frequently asked questions
Are the results accurate?
We use standard formulas with double-precision math. For important financial or medical decisions, consult a professional.
Do you store my data?
No. Calculations run in your browser.
Can I use it on my phone?
Yes, it is mobile-optimized.