Macronutrient Calculator (Protein, Carbs, Fats

Nutritional Science: The Three Energy Macronutrients

Macronutrients provide the structural building blocks and biochemical energy required for human life:

The Energy Densities

• Protein: Essential for muscle protein synthesis, tissue repair, enzyme production, and immune function.

• Carbohydrates: The body's primary high-octane energy fuel for brain metabolism and high-intensity muscular exertion.

• Dietary Fats: Essential for hormone production (testosterone, estrogen), cell membrane integrity, and fat-soluble vitamin absorption (A, D, E, K).

How to Use This Calculator

Enter your Biological Sex — select from Male, Female, Age (Years) (e.g. 30), Body Weight (e.g. 170), Weight Unit — select from Pounds (lbs), Kilograms (kg), Height (e.g. 70 in (5'10") or 178 cm), Height Unit — select from Inches (in), Centimeters (cm), Daily Activity Level — select from Sedentary (Little to no exercise, desk job), Lightly Active (Light exercise 1-3 days/week), Moderately Active (Moderate exercise 3-5 days/week), Fitness / Body Composition Goal — select from Fat Loss / Cutting (-500 kcal/day), Maintain Weight / Recomposition (0 kcal change), Muscle Building / Clean Bulk (+300 kcal/day), and Macronutrient Distribution Style — select from Balanced Macro Split (30% Protein, 40% Carbs, 30% Fat), High Protein / Athletic (40% Protein, 35% Carbs, 25% Fat), Low Carb / Keto (25% Protein, 5% Carbs, 70% Fat). Results update instantly — no submit button needed. Use metric or imperial units as labeled. For the most accurate result, measure height and weight in the morning without shoes.

The Formula

Mifflin-St Jeor BMR & Macronutrient Caloric Density Equations: (Men) = (10 × W_kg) + (6.25 × H_cm) - (5 × Age) + 5 (Women) = (10 × W_kg) + (6.25 × H_cm) - (5 × Age) - 161 = BMR × Activity Multiplier Conversions: Protein = (Target kcal × \%P) / (4 kcal/g), Carbs = (Target kcal × \%C) / (4 kcal/g), Fat = (Target kcal × \%F) / (9 kcal/g)

Worked Example

For example, a 30-year-old male weighing 170 lbs (77.11 kg) at 5'10" (177.8 cm) with light activity aiming for fat loss: Baseline TDEE is 2,410 kcal/day. With a 500 kcal deficit, daily target is 1,910 kcal/day. Under a balanced 30/40/30 split, daily targets are 143g Protein, 191g Carbohydrates, and 64g Dietary Fat.

Understanding Your Result

Current evidence-based protein recommendations: Sedentary adults: 0.8 g/kg body weight (RDA minimum). Active adults: 1.2–1.6 g/kg. Athletes or those building muscle: 1.6–2.2 g/kg. Older adults (65+): 1.2–1.6 g/kg to counter sarcopenia. The RDA (0.8 g/kg) is the minimum to prevent deficiency — not the optimal intake for body composition or longevity. Protein at each meal (25–40g) maximizes muscle protein synthesis; distribution matters as much as total daily amount.