Track daily caffeine intake.
Caffeine intake is the sum of every caffeinated drink, not the strength of any single cup. Adding up cups of coffee and tea against their typical caffeine content gives a daily milligram figure you can compare with the widely cited 400 mg per day guideline for healthy adults, and dividing by body weight shows the dose per kilogram — the figure that actually determines how strongly you feel it.
Daily caffeine load
Total mg = coffee cups x mg per coffee + tea cups x mg per tea; dose per kg = total mg / body weight kg
These figures are population-average estimates for general planning only and are not medical or dietetic advice. Individual energy and nutrient needs vary widely with body composition, activity, medication and health status. Consult a qualified health professional or registered dietitian before making significant changes to what you eat, and especially if you are pregnant or breastfeeding, are under 18, or have a medical condition or a history of disordered eating.
Health authorities commonly cite about 400 mg a day for healthy adults, which is roughly four brewed coffees. This calculator shows your total as a percentage of that 400 mg reference so you can see how close you sit.
Sensitivity tracks dose per kilogram more closely than raw milligrams. Around 3 mg/kg is a typical performance dose and above roughly 6 mg/kg jitteriness and sleep disruption become common, so the mg/kg figure is more informative than the total alone.
They contribute a little — decaf is typically 2-5 mg per cup and a bar of dark chocolate 20-30 mg. Add them into the tea line if you want them included.