Muscle Hypertrophy Macro Calculator
Calculate optimal TDEE and macro splits for muscle growth. Supports Lean Bulk vs. Dirty Bulk strategies with Mifflin-St Jeor accuracy.
About
Muscle hypertrophy requires a precise caloric surplus relative to total daily energy expenditure (TDEE). Eating too few calories limits protein synthesis. Eating too many leads to excessive adipose tissue accumulation. This calculator utilizes the Mifflin-St Jeor equation, widely considered the most reliable basal metabolic rate (BMR) estimator for non-obese individuals, to establish a baseline. It then applies activity multipliers and specific surplus targets based on the user's aggression level (Lean vs. Dirty Bulk).
The macro split is critical. Protein provides the amino acids necessary for repair. Carbohydrates spare protein and fuel glycogen stores for high-intensity training. Fats regulate hormonal function. The 40/40/20 or 30/50/20 splits offered here are standard bodybuilding protocols designed to maximize anabolic windows while minimizing fat gain.
Formulas
The core calculation relies on the Mifflin-St Jeor equation for BMR:
Men:
BMR = 10W + 6.25H − 5A + 5
Women:
BMR = 10W + 6.25H − 5A − 161
Total Expenditure:
TDEE = BMR × ActivityFactor
Where W is weight (kg), H is height (cm), and A is age (years).
Reference Data
| Activity Level | Description | Multiplier (TEF included) |
|---|---|---|
| Sedentary | Office job, no exercise | 1.2 |
| Lightly Active | Light exercise 1-3 days/week | 1.375 |
| Moderately Active | Moderate exercise 3-5 days/week | 1.55 |
| Very Active | Heavy exercise 6-7 days/week | 1.725 |
| Extremely Active | Physical job + Training 2x/day | 1.9 |
| Surplus: Lean Bulk | Minimize fat, slow gain | +250 kcal |
| Surplus: Moderate | Balanced approach | +500 kcal |
| Surplus: Dirty Bulk | Max weight, accept fat gain | +750 to +1000 kcal |