"Espresso has more caffeine per unit volume than most coffee beverages, but because the usual serving size is much smaller, the total caffeine content is less ...
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than a mug of standard brewed coffee. The actual caffeine content of any coffee drink varies by size, bean origin, roast method and other factors, but a typical one ounce serving of espresso usually contains 65 milligrams of caffeine, whereas a typical serving of drip coffee usually contains 150 to 200 mg." - (en.wikipedia.org 06.09.2020)