How macros contribute calories
Protein and digestible carbohydrate each supply approximately four kcal per gram, while fat supplies approximately nine. These general factors are useful for quick arithmetic but do not reproduce every food label exactly.
The 4/4/9 calculation
Multiply protein and carbohydrate grams by four and fat grams by nine, then add the results. Alcohol, sugar alcohols, and fiber-specific energy factors are outside this simplified model.
How to use this calculator
- 1Enter the protein, carbohydrate, and fat grams for the same portion or day.
- 2Use zero for a macro that is absent.
- 3Calculate the total and compare each nutrient's calorie contribution.
Understanding your result
The result is the energy implied by your macro entries. It does not judge food quality or establish whether the amount suits your needs. For logging packaged food, its supplied nutrition label may use more specific factors.
Assumptions & limitations
- Total carbohydrate can include fiber and polyols with different energy values.
- Label rounding, alcohol, and food-specific factors can cause legitimate differences.
Frequently asked questions
Why does fat have more calories per gram?+
Fat contains more metabolizable energy per gram than protein or carbohydrate. The general conversion factors are nine versus four kcal per gram.
Should I subtract fiber from carbohydrate?+
The answer depends on your label system and intended calculation. This tool applies four kcal to every carbohydrate gram you enter and does not separately model fiber.
Does this include alcohol calories?+
No. Alcohol supplies about seven kcal per gram and is not one of the three inputs, so alcoholic drinks may contain energy not captured here.
Can I enter a whole day's macros?+
Yes. The arithmetic works for a food, meal, recipe, or day as long as all three entries refer to the same amount.
