Fitness calculators
Sleep Cycle Calculator
Pick a wake-up time and see bedtime options based on ~90-minute cycles plus a short fall-asleep buffer.
Estimates only — not medical advice. Formulas are simplified screening tools. Talk to a qualified clinician for health decisions.
6 cycles
Bedtime 21:45
5 cycles
Bedtime 23:15
4 cycles
Bedtime 00:45
3 cycles
Bedtime 02:15
How to use
- Enter the time you want to wake up.
- Review bedtime suggestions for 3–6 cycles.
- Choose the option that fits your schedule.
Features
- 90-minute cycle model
- 15-minute fall-asleep buffer
- Multiple bedtime options
Privacy & how it works
This calculator runs entirely in your browser with JavaScript. Your inputs are not uploaded to ToolsWeb servers for this tool. Privacy Policy · Disclaimer.
FAQ
Are sleep cycles always 90 minutes?expand_more
No. Cycle length varies by person and night. Treat results as planning hints.
Is this calculator free?expand_more
Yes. No signup required.
Are my numbers uploaded?expand_more
No. Calculations run in your browser. Inputs are not sent to ToolsWeb servers for this tool.
Is this professional advice?expand_more
No. Results are estimates for general information. See our Disclaimer for health, finance, and related tools.