Protein, carbohydrates, fat, and alcohol are the food components that contribute Caloriesto the foods that you eat. They, however, do not contribute Calories equally. As you can see from the table below, protein and carbohydrate contribute significantly fewer Calories per gram than fat or alcohol. Common conversion factors, referred to as the 4-4-9 formula, are most often used by manufacturers to calculate Calorie values for their products. More specific conversion factors based on food type, called Atwater factors, are commonly used by the USDA database to calculate Calorie values forfoods. The FDA labeling regulations allow six methods to calculate Calories reported on U.S. Nutrition Facts labels. Thesecalculations include 4-4-9, variations of 4-4-9, Atwater factors, and other methods. The method used to report Caloriesfor each ingredient in the database may vary.