
ZZZcalc.com
Bedtime calculator based on 90-minute sleep cycles
What it does
ZZZCalc calculates the ideal time to go to bed or wake up based on 90-minute sleep cycles plus the average 14 minutes it takes to fall asleep. Most bedtime advice ignores sleep cycles entirely — waking mid-cycle causes grogginess no matter how many hours you slept. Features: bedtime calculator, wake-up calculator, shift worker mode, and nap calculator. Completely free, no account required.
Does the same job
all alternatives →
Sleep Cycle CalculatorMay 2026 · navi-resources.com · ▲1Free sleep calculator based on 90-min cycles
Sleep CalculatorJul 2026 · sleepcalculator.io · ▲2Sleep Calculator – Find Your Best Bedtime and Wake-Up Time
Best Time For BedMay 2026 · besttimeforbed.com · ▲2Find your perfect bedtime based on 90-minute sleep cycles
Sleep Calculator UKAug 2026 · sleepcalculator.org.uk · ▲1Calculate your ideal sleep and wake times — no signup.

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