When people talk about having “a cup of coffee,” they don’t necessarily mean 8 ounces (236 milliliters). For example, many people go for the large size of coffee at McDonald’s restaurants and Starbucks, at 20 ounces (591 milliliters). Or at home, they may have a 12- to 16-ounce mug.
So when you read guides online that say an 8-ounce cup of drip java has about 163 mg of caffeine, you can more than double the amount of the stimulating chemical for a 20-ounce size. Drip coffee is the kind that drips through a filter to produce that cup or mug of the elixir that so many people say they can’t start their day without.