# Caffeine Intake Calculator Track your daily caffeine intake from coffee, tea, energy drinks, and supplements. Check if you are within FDA safe limits based on your body weight. ## What this calculates 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. ## Inputs - **Cups of Coffee (8 oz)** (cups) — min 0, max 20 - **Cups of Tea (8 oz)** (cups) — min 0, max 20 - **Energy Drinks (16 oz)** (cans) — min 0, max 10 - **Caffeine Pills/Supplements** (pills) — min 0, max 10 - **Body Weight** (kg) — min 30, max 250 ## Outputs - **Total Caffeine** — Total daily caffeine intake - **Caffeine per kg Body Weight** — Caffeine relative to your body weight - **Percentage of Safe Limit** — Percentage of the FDA 400mg daily limit - **Recommendation** — formatted as text — Assessment and guidance based on your intake ## Details 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. ## Frequently Asked Questions **Q: How much caffeine is too much?** A: The FDA recommends no more than 400 mg per day for healthy adults. Symptoms of too much caffeine include anxiety, insomnia, digestive issues, rapid heartbeat, muscle tremors, and irritability. Doses above 1,200 mg can be dangerous, and single doses above 10,000 mg can be lethal. **Q: Does caffeine tolerance affect the safe limit?** A: Regular caffeine consumers develop tolerance, meaning they may feel fewer effects at the same dose. However, tolerance affects subjective effects (alertness, jitteriness) more than cardiovascular effects (blood pressure, heart rate). The 400mg guideline applies regardless of tolerance level. **Q: How long does caffeine stay in your system?** A: Caffeine has a half-life of approximately 5–6 hours in healthy adults, but this can range from 3 to 9 hours depending on genetics (CYP1A2 enzyme variants), liver function, pregnancy (half-life doubles), and medications. It takes about 10‒12 hours for caffeine to be mostly eliminated. **Q: Is caffeine safe during pregnancy?** A: ACOG (American College of Obstetricians and Gynecologists) recommends limiting caffeine to 200 mg per day during pregnancy — about two 8-oz cups of coffee. Higher intake has been associated with increased risk of miscarriage and low birth weight, though the evidence is not conclusive for moderate amounts. --- Source: https://vastcalc.com/calculators/health/caffeine Category: Health & Fitness Last updated: 2026-04-21