According to SELF Nutrition Data, there is 116 milligrams of potassium in 8 ounces of coffee. This accounts for 3 percent of a person's daily value. One cup of coffee contains about 1/4 the amount of potassium that is found in a medium-sized banana.
In addition to potassium, SELF Nutrition Data also explains that one cup of coffee contains 94.8 milligrams of caffeine. Other vitamins and minerals found in coffee include vitamin K, riboflavin, niacin, folate, pantothenic acid, choline, calcium, magnesium, phosphorus and manganese. Coffee is very low in saturated fat, cholesterol and sodium. This information is based on coffee that is brewed with tap water.