A medium-sized banana has between 27 and 30 grams of carbohydrates, with 3 grams of dietary fiber and 14 to 19 grams of sugar. A medium-sized banana is 7 to 8 inches long and weighs 126 grams.
A medium-sized banana has up to 0.5 gram of fat, with up to 0.15 gram of saturated fat and up to 0.1 gram of polyunsaturated fat. There is approximately 1 gram of protein and up to 1 milligram of sodium. A medium-sized banana has 450 milligrams of potassium, 34 milligrams of magnesium, 9 milligrams of vitamin C, 81 IU vitamin A, 0.8 gram of niacin, 0.5 gram of vitamin B6, 0.3 gram of iron, 0.3 gram of manganese, 0.1 gram of riboflavin and 25 micrograms of folate.