Calories from Macros Calculator
Calculate total calories and percentage split from grams of protein, carbs, and fat
Calculated from 150g protein, 220g carbs, and 65g fats
| Nutrient | Grams | Energy Factor | Total Energy | % Energy |
|---|---|---|---|---|
| Protein | 150 g | 4.0 kcal/g | 600 kcal | 29% |
| Carbohydrate | 220 g | 4.0 kcal/g | 880 kcal | 43% |
| Dietary Fat | 65 g | 9.0 kcal/g | 585 kcal | 28% |
Mathematical Formula & Scientific Methodology
Formula: Atwater General Energy System
Total Kcal = (Protein × 4) + (Carbohydrates × 4) + (Fat × 9)Applies standard USDA Atwater coefficients to convert mass of macronutrients into bioavailable thermal energy.
Model Assumptions
- Standard mixed diet
Variables & Standard Units
| Symbol | Physiological Meaning | Unit |
|---|---|---|
| Protein | Grams of dietary protein (4 kcal/g) | g |
| Carbs | Grams of dietary carbohydrates (4 kcal/g) | g |
| Fat | Grams of dietary fat (9 kcal/g) | g |
Scientific Limitations
- Insoluble fiber has lower metabolizable energy (~2 kcal/g or less)
Peer-Reviewed Scientific Citations
Obesity: preventing and managing the global epidemic. Report of a WHO consultation (2000)
World Health Organization (2000) — WHO Technical Report Series, 894, 1-253
Key Finding: Standard international adult BMI classifications: Underweight (<18.5), Normal (18.5-24.9), Overweight (25.0-29.9), Obesity Class I (30.0-34.9), Class II (35.0-39.9), Class III (>=40.0).
Frequently Asked Questions
Related Calculators & Next Steps
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