How this calculator works
Caffeine content depends on the drink, the serving size and how it was made. An espresso is small but concentrated, so a 30 mL shot carries about as much caffeine as a 240 mL cup of tea. Filter coffee is more concentrated than instant, and an energy drink can carry more than a cola of the same size. Health Canada recommends no more than 400 mg a day for healthy adults, 300 mg for people who are pregnant or breastfeeding, and 2.5 mg per kilogram of body weight a day for children and adolescents. The limit is a public health guideline, not a personal tolerance: how caffeine feels depends on habit, sleep, medication and genetics, and a person who feels fine at 500 mg is still above the recommended intake. The figures here are typical values; a coffee shop can vary by a third or more.
Formula
caffeine per serving = caffeine per 100 mL x serving size in mL / 100. total = per serving x servings. daily limit = 400 mg adult, 300 mg pregnant or breastfeeding, or 2.5 mg/kg for under 18. share of limit = total / limit. servings to the limit = limit / caffeine per serving.
Worked example
One 240 mL brewed coffee at 40 mg per 100 mL carries 40 x 2.4 = 96 mg, which is 96 / 400 = 24 percent of an adult limit. Three of them is 288 mg, or 72 percent. Two 30 mL espressos at 213 mg per 100 mL carry 213 x 0.3 = 63.9 mg each, so 127.8 mg for the two. A 60 kg adolescent has a limit of 2.5 x 60 = 150 mg, so one 240 mL brewed coffee is already 64 percent of it.
Advertisement
Frequently asked questions
Is 400 mg of caffeine a day safe?
Health Canada sets 400 mg a day as the recommended maximum for healthy adults, about three 240 mL cups of brewed coffee. It is a guideline for the general population, not a guarantee for everyone, and people with heart conditions, anxiety or sleep problems may need less.
How much caffeine can a child have?
Health Canada recommends no more than 2.5 mg per kilogram of body weight a day for children and adolescents. For a 40 kg child that is 100 mg, about one large cup of brewed coffee. Energy drinks are not recommended for children at all.
Does decaf have caffeine?
A little. Decaf coffee is typically under 1 mg per 100 mL, so a 240 mL cup has around 2 mg, against around 96 mg for regular coffee. It is not zero, which matters for people who are very sensitive or on a strict medical limit.
Why do coffee shop values vary so much?
The amount of ground coffee, the brew time and the size of the shot all change the cup. A large latte may have two shots where a small one has one, and a strong filter brew can carry more caffeine than the figure here. Use the calculator as a comparison between drinks rather than a laboratory measure.