Health & Fitness calculator
Sleep Calculator
Find the best times to wake up or go to bed based on sleep cycles.
About the sleep calculator
The sleep calculator finds optimal bedtimes based on 90-minute sleep cycles.
How to use this calculator
- 1
Choose wake time
Select when you need to wake up.
- 2
View results
See recommended bedtimes for 4, 5, or 6 complete sleep cycles.
How the calculation works
Sleep cycles are ~90 minutes. Falling asleep takes ~15 minutes. Optimal: 5-6 complete cycles (7.5-9 hours).
Example: Wake at 7:00 AM: Go to bed at 9:45 PM, 11:15 PM, or 12:45 AM.
Important health disclaimers
These calculators provide estimates based on population averages. Individual results vary based on genetics, body composition, medical conditions, and medications. Always consult a healthcare provider before starting a new diet or exercise program, especially if you have underlying health conditions.
Understanding body composition metrics
BMI doesn't distinguish muscle from fat. Body fat % is more accurate but depends on measurement technique. TDEE varies day-to-day based on activity. Macro targets are starting points — adjust based on your results, energy levels, and goals. Hydration needs increase with exercise, heat, and altitude.
Important limitations
This tool provides a mathematical estimate based only on the values entered. It does not account for regulations, taxes, lender fees, market conditions, or individual circumstances. Results are for planning purposes only — consult a qualified professional for regulated, medical, financial, or construction decisions.
Frequently asked questions about sleep calculator
How accurate is the sleep calculator?+
The calculation follows the displayed formula and retains full numeric precision before formatting the result.
Can I use the result professionally?+
Use it as a planning estimate. Confirm regulated, medical, financial, or construction decisions with a qualified professional.