CaloriMateConvert calories to grams of a known component
If you know how much energy is supplied specifically by protein, carbohydrate, fat or alcohol, divide that component energy by its general kcal-per-gram factor. For example, 100 kcal from protein is 25 g protein; 100 kcal from fat is about 11.1 g fat.
Do not enter the total energy of a mixed meal and treat the answer as its food weight. A food contains water and a mixture of components. You need a matching food energy density or nutrient breakdown to connect its total calories with edible grams. These general factors do not capture all food-specific factors, fiber or label rules.
Why there is no universal grams-to-calories ratio
| Component | General kcal per gram |
|---|---|
| Protein | 4 |
| Carbohydrate | 4 |
| Fat | 9 |
| Alcohol | 7 |
One hundred grams of cucumber and one hundred grams of olive oil have very different energy content. Use a matching food record or product label when you know total food weight. The 4/4/9/7 calculator is for grams of the components, not for guessing a food composition.
Fiber, polyols, organic acids, label rounding and food-specific factors can make label/database energy differ from this simplified sum. Do not subtract fiber and count it twice without checking the labeling system.
Sources & methods
- FAO: food energy conversion factorsGeneral 4/4/9/7 factors and 1 kcal = 4.184 kJ. Food-specific factors and fiber can differ.
- USDA FoodData Central: SR Legacy reference foodsPer 100 g edible material. Individual food names and SR Legacy NDB numbers appear in the reference tables.