Why do calories not exactly match protein, carbs and fat?

Calsa keeps the energy stated by the food source instead of replacing it with a simple calculation from protein, carbohydrate and fat. Labels and databases can use different energy factors, definitions and rounding, so the numbers do not always match that calculation exactly.

Also check fibre, the carbohydrate definition and whether you are comparing kcal with kJ or a serving with 100 g. Open the source to see the basis. If the label still disagrees for the same food and amount, report it or make a private correction from the label.