A whole wheat hamburger bun contains 96 calories, and a white hamburger bun contains 100 calories, according to the U.S. Department of Agriculture. Calories are a way to measure the amount of energy that can be obtained by a food.
Not all calories are considered to be equal. Some contribute nutrients to the body, and others are considered to be empty calories. Empty calories do not contribute nutrients and include the solid fats and sugars that are often added to foods. A white hamburger bun has eight empty calories, whereas a whole wheat hamburger bun has 21 empty calories, according to the USDA.