Safe Caffeine Limit Calculator
Estimate a safe daily caffeine limit from your body weight, with the 400 mg general adult cap and a lower pregnancy threshold, in milligrams and cups of coffee.
How it works
Weight guide = 3 mg × kg · Adult cap = min(400 mg, weight guide) · Pregnancy cap ≈ 200 mg · Cups = limit ÷ 95 mg
Health authorities such as the US FDA and EFSA consider up to about 400 mg of caffeine a day safe for most healthy adults, with single doses under roughly 200 mg. A body-weight guide of about 3 mg per kilogram gives a personalised moderate intake, and the calculator uses the lower of that and the 400 mg cap. Pregnant and breastfeeding people are usually advised to stay under 200 mg. Sensitivity varies widely with genetics, medication and tolerance, so these are population limits, not personal targets.
Worked example
A 70 kg adult: 3 mg × 70 = 210 mg from the weight guide, which is below the 400 mg cap, so the suggested limit is about 210 mg — roughly 2.2 cups of brewed coffee at 95 mg each.
Frequently asked questions
How much caffeine is too much?
For healthy adults, intakes above about 400 mg a day, or single doses above roughly 200 mg, are where side effects like jitteriness, insomnia and a racing heart become more likely. Very high doses can be dangerous.
How much caffeine is in a cup of coffee?
An 8 oz cup of brewed coffee has about 95 mg on average, but espresso, energy drinks, tea and cola vary a lot. Check labels, since a large coffee-shop drink can hold two to three times a home cup.
Why is the pregnancy limit lower?
Caffeine crosses the placenta and is cleared more slowly in pregnancy. Major bodies advise staying under about 200 mg a day, though some recommend avoiding it — discuss with your clinician.
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Educational estimate using standard published formulas — not medical, dietary or nutritional advice. Individual needs vary with health status, medication and activity; consult a qualified clinician or dietitian before making changes.