Macronutrient calories calculator
Add up calories from protein, carbs and fat from the grams and see each one's share.
Per gram: protein 4 kcal, carbs 4 kcal, fat 9 kcal. That is why fat carries more calories per gram.
How the calculation works
Calories come from the Atwater factors: protein × 4 + carbs × 4 + fat × 9. Multiply each macro's grams by its factor and add them up. The share shows how much each one is of the total.
Examples
- 30 g protein + 40 g carbs + 10 g fat: 120 + 160 + 90 = 370 kcal.
- Fat yields more than double per gram (9 vs 4 kcal) — it weighs heavily on the total.
Frequently asked questions
What about alcohol?
Alcohol has 7 kcal per gram, but it is not a nutritional macronutrient and is not included here.
What are the Atwater factors?
The average energy values of each macro: 4 kcal/g for protein and carbs, 9 kcal/g for fat. Food labels use this basis.
Why does the sum sometimes differ from the label?
Labels round and count fiber (which yields less energy). The difference is usually small.
How many calories per macronutrient?
Protein and carbohydrate have 4 kcal per gram, fat 9 and alcohol 7. Fibre yields about 2.
Why does my math differ from the label?
Fibre counts partially, sugar alcohols yield less, and labelling rules allow rounding.
What is the best macro split?
The one you can sustain. As a reference: 1.6–2.2 g of protein per kilo, fat not below ~0.8 g/kg, carbohydrate for the rest.
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See all →Updated on June 30, 2026 · by Rafael Rossi · Methodology & sources