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About Sleep Caffeine
A small, independent project with one job: turn solid sleep and caffeine science into numbers you can use tonight.
What we do
Sleep Caffeine builds free calculators around the questions people actually search for — how much caffeine is safe, how long it lasts, and when to sleep. No accounts, no email walls, no selling your data.
How we calculate
Every calculator is built on published guidelines and peer-reviewed research, not opinion:
- Caffeine limits — U.S. FDA 400 mg/day guidance for healthy adults, ACOG's 200 mg limit in pregnancy, and a common ~6 mg/kg per-weight guideline.
- Caffeine half-life — a standard single-compartment model with a ~5-hour half-life (typical adult range 3–7 hours).
- Sleep cycles — the well-documented ~90-minute cycle plus typical sleep-onset latency.
We show our assumptions on each page so you can judge the numbers yourself. Caffeine content and metabolism vary a lot between people, brands and brews — our results are informed estimates, not lab measurements.
Not medical advice
Sleep Caffeine is educational. It can't account for your medications, health conditions or pregnancy. For decisions about your health, talk to a qualified healthcare professional.
How we stay free
The site is supported by display advertising and Amazon affiliate links — when you buy through a link we may earn a small commission at no extra cost to you. That keeps every calculator free. We only suggest products that genuinely relate to the page you're on.