Know exactly
when to sleep.

18 free calculators for bedtime, wake time, sleep debt, chronotype, and more. Built on sleep science, not guesswork.

Try the Sleep Cycle Calculator →Bedtime Calculator →

Based on sleep cycle scienceShareable resultsMobile-friendlyNo account needed

Sleep Cycles Bedtime Wake-Up Time Sleep Debt Caffeine Cutoff Chronotype Sleep Science Articles →

Timing

Bedtime, wake time, nap length, caffeine cutoff.

Health

Sleep debt, quality score, how much you need.

Life Situations

New parents, shift workers, and travellers.

Circadian & Chronotype

Chronotype quiz, melatonin timing, schedule fixing.

Sleep science explained

All articles →

Sleep Cycles Explained

What happens in each 90-minute cycle, and why waking mid-cycle feels terrible.

What Is a Chronotype?

Lion, Bear, Wolf, Dolphin — and the biology that determines which one you are.

Caffeine and Sleep

Caffeine's 5–7 hour half-life means your 2pm coffee is still 50% active at 9pm.

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Built on real sleep science.

Every calculator is built on peer-reviewed research: 90-minute sleep cycles, NSF age-based guidelines, caffeine half-life pharmacology, and circadian rhythm biology. The math is correct. The tools are free. No sign-up required. Learn about our methodology →