We do not calculate Calories based on the 4-4-9 formula.
Our nutrition information is provided by our Nutrition API and consists primarily of FoodData Central Data. FoodData Central uses Atwater Factors. The system is based on the heats of combustion of protein, fat and carbohydrate, which are corrected for losses in digestion, absorption and urinary excretion.
Note: Atwater Factors tend to be more precise. Different foods have differing caloric contributions per gram. For example, 1g of fat from one food may yield 8.4 Calories, while 1g of fat from another food may yield 9.37 Calories. For fat, the values range very near 9 Calories, but it is not exactly 9 Calories. Same concept with a gram of Protein or Carbohydrate. Generally you'll find Atwater Factors to result in slightly less total Calories than when you approximate using 4-4-9.