Caffeine Calculator
Calculate daily caffeine from coffee, espresso, tea, energy drinks, and soda.
Compares total against the 400 mg FDA limit and shows half-life clearance by hour.
Caffeine is a central nervous system stimulant found naturally in coffee, tea, cocoa, and added to energy drinks and sodas. Tracking your daily intake helps you stay within safe limits and manage sleep and anxiety.
Formula: Total Daily Caffeine = Σ(Caffeine per Serving × Number of Servings) Caffeine per mg/kg = Total Caffeine ÷ Body Weight in kg
What each variable means:
- Caffeine per Serving — varies significantly by preparation method and brand.
- Number of Servings — count each cup, shot, or can separately.
- Body Weight — used to calculate weight-adjusted intake for sensitivity assessment.
Caffeine content reference (per serving):
- Drip coffee (8 oz): 80–135 mg (average ~95 mg)
- Espresso (1 shot, 1 oz): 47–75 mg (average ~63 mg)
- Cold brew (8 oz): 100–200 mg
- Black tea (8 oz): 40–70 mg
- Green tea (8 oz): 20–45 mg
- Monster Energy (16 oz): 160 mg
- Red Bull (8.4 oz): 80 mg
- Coca-Cola (12 oz): 34 mg
- Dark chocolate (1 oz): 12–25 mg
- Decaf coffee (8 oz): 2–15 mg (not zero!)
Safe daily limits:
- Healthy adults: up to 400 mg/day (FDA guideline)
- Pregnant women: under 200 mg/day
- Adolescents (12–18): under 100 mg/day
- Children under 12: avoid entirely
Worked example: Morning: 2 cups drip coffee (95 mg each = 190 mg) Lunch: 1 can Diet Coke (46 mg) Afternoon: 1 shot espresso (63 mg)
Total = 190 + 46 + 63 = 299 mg — within safe adult limits.
Half-life note: Caffeine has a half-life of approximately 5–6 hours. A 3 PM espresso still has ~31 mg active at 9 PM, which can disrupt sleep.