Macro Calculator
Calculate balanced protein, carbohydrate, and fat grams for any daily calorie intake
660 kcal from dietary protein
| Macronutrient | Daily Grams | Calories | % Total Energy |
|---|---|---|---|
| Protein | 165 g | 660 kcal | 30% |
| Carbohydrates | 220 g | 880 kcal | 40% |
| Dietary Fat | 73 g | 660 kcal | 30% |
| Total | — | 2200 kcal | 100% |
Mathematical Formula & Scientific Methodology
Formula: Atwater General Energy Factor System
Total Kcal = (Protein g × 4) + (Carbohydrate g × 4) + (Fat g × 9)Applies standard Atwater bomb calorimetry factors with adjustments for human urinary and fecal heat losses.
Model Assumptions
- Standard whole-food dietary bio-availability
Variables & Standard Units
| Symbol | Physiological Meaning | Unit |
|---|---|---|
| Protein | 4 kilocalories per metabolizable gram | kcal/g |
| Carbohydrate | 4 kilocalories per metabolizable gram | kcal/g |
| Fat | 9 kilocalories per metabolizable gram | kcal/g |
Scientific Limitations
- Dietary fiber reduces net metabolizable carbohydrate energy (~2 kcal/g for soluble fiber)
Peer-Reviewed Scientific Citations
A new predictive equation for resting energy expenditure in healthy individuals (1990)
Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO (1990) — The American Journal of Clinical Nutrition, 51(2), 241-247
Key Finding: Mifflin-St Jeor equation is accurate within ±10% of measured REE in non-obese and obese individuals, recommended by the Academy of Nutrition and Dietetics as the most reliable standard equation.
Frequently Asked Questions
Related Calculators & Next Steps
Protein Calculator
Calculate optimal daily protein targets based on body mass and training activity
Carbohydrate Calculator
Calculate daily carbohydrate requirements for endurance, gym performance, or low-carb diets
Fat Intake Calculator
Calculate essential dietary fat requirements for hormone synthesis and vitamin absorption