Caffeine Intake Calculator
Caffeine is the most widely consumed psychoactive substance in the world. This calculator tracks your total daily caffeine intake from common sources and evaluates whether you are within the FDA's recommended safe limit of 400mg per day for healthy adults.
The FDA considers 400 milligrams of caffeine per day to be a safe amount for most healthy adults — roughly equivalent to four 8-ounce cups of brewed coffee. A body weight-based guideline of approximately 6 mg/kg/day provides an additional safety check, which is particularly relevant for smaller individuals who may reach unsafe levels before hitting the absolute 400mg threshold.
Caffeine content varies significantly by source and preparation. A standard 8-ounce cup of brewed coffee contains about 80–100 mg (average ~95 mg). Brewed tea averages ~47 mg per 8-ounce cup. A 16-ounce energy drink typically contains 140–180 mg (~160 mg average), and caffeine pills usually contain 200 mg per tablet. Espresso is more concentrated (~63 mg per 1-oz shot) but served in smaller volumes.
Caffeine's half-life is approximately 5–6 hours in healthy adults, meaning half the caffeine from a 2 PM coffee is still in your system at 7–8 PM. Sleep experts recommend avoiding caffeine at least 6–8 hours before bedtime. Pregnant women should limit intake to 200 mg/day per ACOG guidelines. This calculator is for general informational purposes; individual sensitivity varies widely.