Studies suggest that moderate amounts of caffeine are not harmful. How much is moderate? One hundred to 200 mg (one to two 5-ounce cups of coffee) each day is the limit that some doctors suggest, but each person is a little different. How caffeine affects people varies with their size, their sex, and how sensitive they are to caffeine’s effects. Experts agree that 600 mg (four to seven cups of coffee) of caffeine or more each day is too much.