How this calculator works
Coffee itself carries almost no energy, so the health question is about the caffeine and what is added. The caffeine comes from the brew method and the dose: an espresso shot delivers its caffeine in 30 mL, a drip cup in 240 mL, and instant coffee much less than either. Bean variety matters more than roast: robusta contains around 1.4 times the caffeine of arabica, while a dark roast does not have more caffeine than a light one, even though it tastes stronger. Milk and sugar are where the calories and the added sugar come from, and a spoonful per cup added three times a day is a real amount of sugar. Health Canada sets 400 mg of caffeine a day for healthy adults, and the World Health Organization suggests keeping free sugars under 10 percent of energy, about 50 g on a 2,000 kcal diet.
Formula
caffeine = cups x caffeine per cup x bean factor, where the per cup figures are 95 mg for drip and French press, 64 mg for an espresso shot, 80 mg for AeroPress, 30 mg for instant and 47 mg for a simple infusion. Added sugar = cups x teaspoons x 4 g. Calories from add-ins = cups x milk volume x milk energy + sugar x 4 kcal/g.
Worked example
Two 240 mL drip cups from arabica beans carry 2 x 95 = 190 mg of caffeine, or 47.5 percent of the 400 mg adult limit. With 30 mL of cow's milk in each and one teaspoon of sugar, the added sugar is 2 x 4 = 8 g, which is 16 percent of the 50 g reference, and the calories from the add-ins are 2 x 30 x 0.61 + 8 x 4 = 36.6 + 32 = 68.6 kcal. Two espressos instead carry 2 x 64 = 128 mg, leaving more room under the limit.
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Frequently asked questions
Does a dark roast have more caffeine?
No. Roasting darkens the bean and changes the flavour, but it does not add caffeine, and because a dark roasted bean weighs slightly less after longer roasting, a scoop can contain a little less caffeine. Robusta beans, not the roast, are the big variable.
How much coffee is too much?
Health Canada recommends no more than 400 mg of caffeine a day for healthy adults, which is about three 240 mL drip cups. Pregnancy and breastfeeding reduce the limit to 300 mg, and children and adolescents should stay under 2.5 mg per kilogram. The limit is about caffeine, not coffee, so tea, cola, energy drinks and chocolate count too.
Is coffee with milk and sugar unhealthy?
Coffee itself is not the problem; the additions can be. A large flavoured drink with syrup and cream can carry more sugar and energy than a dessert. Keeping the milk modest and the sugar to a spoon or none keeps the drink close to plain coffee.
Does coffee count towards my water intake?
It is a drink and it contributes fluid, but it is also a mild diuretic, so it does not replace water entirely. Water remains the best default drink, and coffee is best treated as a drink with a caffeine dose rather than a hydration strategy.