Caffeine Safe Limit Calculator

About this calculator

Safe daily caffeine limits are generally set as an absolute ceiling — the US FDA cites roughly 400 mg/day as not typically associated with dangerous effects for most healthy adults — alongside weight-based single-dose guidance, since caffeine sensitivity and toxicity risk scale with body mass; some guidelines cap single doses around 200 mg or use a per-kilogram threshold (commonly cited around 6 mg/kg for a cautious per-dose ceiling, with lower thresholds recommended for adolescents).

Physicians, sports nutritionists, and energy-drink and supplement manufacturers reference weight-adjusted caffeine limits because a fixed daily number doesn't account for the wide range of adult body sizes, and because acute overconsumption (rather than typical daily intake) is the greater safety concern — caffeine toxicity symptoms like rapid heartbeat, anxiety, and in rare severe cases cardiac events are dose-dependent and disproportionately affect lighter individuals at the same absolute intake.

This calculator takes your body weight and returns an estimated safe daily caffeine limit and a safe single-dose limit, scaled to your weight.