Coffee has a higher caffeine content than a cappuccino. Brewed coffee contains an average of 20 milligrams of caffeine per fluid ounce, while cappuccino contains approximately 13 milligrams of caffeine per fluid ounce.
The precise amount of caffeine in a beverage varies depending on the serving size, brand, brewing time and method of preparation. For instance, coffee brewed from grounds contains nearly three times as much caffeine as instant coffee.
Small quantities of caffeine are harmless to most people and in fact, drinking coffee each day has been associated with a decreased risk of gallstones, Alzheimer's disease, Parkinson's disease and suicide, according to the Center for Science in the Public Interest. In large doses, however, caffeine can cause anxiety and difficulty sleeping. The Mayo Clinic recommends keeping caffeine consumption to under 500 milligrams per day.