The average weight of an unpeeled medium-sized banana, which measures 7 inches in length, is 6.5 ounces. Without the peel, a medium banana weighs approximately 4.2 ounces. A peeled large banana, measuring 8 to 9 inches, weighs 4.8 ounces, or 7.5 ounces with the peel.
A peeled extra-large banana, measuring over 9 inches in length, weighs approximately 5.4 ounces, or 8.5 ounces with the peel. The smallest banana, commonly called a baby banana, weighs approximately 1.9 ounces peeled and 3 ounces with the peel. A medium-sized banana contains 105 calories, 4 grams of fat, 1 gram of protein, 3 grams of fiber and 27 grams of carbohydrates.