Start lower than you think
Performance benefits are often studied around 3–6 mg/kg, but many people respond to less and experience more side effects as dose rises. This calculator deliberately starts lower and caps the displayed range at 400 mg.
Count all sources: coffee, energy drinks, pre-workout, tea, medication and the rest of the day’s intake.
When to avoid personalized estimates
Pregnancy, adolescence, cardiovascular conditions, anxiety, medication use and caffeine sensitivity need different considerations. Caffeine can also disrupt sleep even when taken hours before bed. This tool is for healthy adults and does not replace individualized medical guidance.
Sources
- Guest NS et al. ISSN position stand: caffeine and exercise performance, 2021.
- EFSA Panel on Dietetic Products. Scientific opinion on the safety of caffeine, 2015.
Reviewed: August 16, 2026.