Muscle Gain (Bulking) Calculator & Macros
Calculate daily surplus for Lean vs Dirty bulk strategies. Includes Macro Split (Protein/Fat/Carbs) generator.
About
Muscle hypertrophy requires a sustained, quantified caloric surplus. Generic estimators often fail by ignoring the immense variability in Total Daily Energy Expenditure (TDEE) and the macronutrient partitioning required for different body types. A "Dirty Bulk" often leads to excessive adipose tissue gain, while a "Lean Bulk" aims to maximize the anabolic window with minimal fat accumulation.
This calculator utilizes the Mifflin-St Jeor equation—considered the gold standard for clinical accuracy—to establish a metabolic baseline. It then overlays customizable surplus targets and macro splits (Protein/Fat/Carb ratios) to generate precise gram-based diet targets for athletes and bodybuilders.
Formulas
BMR (Mifflin-St Jeor):
TDEE:
TDEE = BMR × ActivityFactor
Macro Density:
Protein = 4 kcal/g | Carbs = 4 kcal/g | Fat = 9 kcal/g
Reference Data
| Bulking Strategy | Surplus (kcal/day) | Expected Weight Gain (weekly) | Rec. For |
|---|---|---|---|
| Maingain / Recomp | +0 to +100 | 0.0 - 0.1 kg | Advanced Lifters |
| Lean Bulk (Standard) | +250 | 0.2 - 0.3 kg | Intermediates |
| Aggressive Bulk | +500 | 0.4 - 0.5 kg | Novices / Teens |
| Dirty Bulk | +750+ | 0.7+ kg | Hardgainers Only |