Nutrition & Calories
Calories from Macronutrients Calculator
Turn grams of protein, carbs, and fat into calories, and see what share comes from each.
Measurement System PreferenceAuto-saved
Currently active across all 60 calculators: US Customary (cups, tbsp, oz, °F, in)
Total calories
455 kcal
Net Carbs: 42g (Total Carbs 50g - Fiber 8g)
Based on standard USDA Atwater General Factors (Protein: 4 kcal/g, Carbohydrate: 4 kcal/g, Fat: 9 kcal/g). Actual commercial food labels may vary slightly due to specific food heat-of-combustion factors and fiber deductions.
Protein: 26.4% (120 kcal)Carbs: 44% (200 kcal)Fat: 29.7% (135 kcal)
How to use this calculator
- 1Enter grams of protein, carbohydrates, and fat (from a label or the Recipe Calorie Calculator).
- 2Optionally enter fiber to see net carbs.
- 3Read the total calories and the colored bar showing where they come from.
Tip: Protein and carbs give 4 calories per gram, fat gives 9.
How it's calculated
Total Calories = (Protein × 4) + (Carbohydrates × 4) + (Fat × 9)
We do the math at full precision and only round the final answer, so the numbers you see are as close as kitchen measurements allow. The assumptions and limits are listed alongside.
Worked example
Scenario: A meal with 25g protein, 40g carbs, and 12g fat.
InputsProtein: 25g, Carbs: 40g, Fat: 12g
Calculation(25 × 4) + (40 × 4) + (12 × 9) = 100 + 160 + 108 = 368 kcal
Result368 kcal (27% Protein, 43% Carbs, 29% Fat)
Common questions
Why does fat have 9 calories per gram while protein and carbs have 4?
Fat is a more concentrated fuel. Its molecules contain more carbon and hydrogen and less oxygen, so your body gets more energy from each gram.