About

Bulking is a controlled process of consuming a caloric surplus to maximize muscle hypertrophy. The challenge lies in the fine line between gaining muscle and gaining excessive fat. A generic approach often leads to "dirty bulking," resulting in rapid weight gain that is mostly adipose tissue, requiring a long, painful cutting phase later.

This tool puts you in control of the surplus. By selecting a strategy - from a conservative "Lean Bulk" designed to minimize fat gain, to a "Dirty Bulk" for hardgainers who struggle to put on mass - you can visualize the outcome. The calculator breaks down macronutrients to ensure that the extra calories fuel protein synthesis and glycogen replenishment rather than just fat storage.

Formulas

The core mechanic of bulking is the energy surplus. The projected weight gain is derived from the standard energetic value of tissue:

Gain_kg/week ≈ Surplus_daily × 77700

Optimal protein intake during a bulk is often set higher to support the increased rate of protein synthesis:

Protein = 1.6 to 2.2 × BodyWeight_kg

Reference Data

Bulking Strategy	Surplus (kcal)	Est. Weekly Gain	Fat/Muscle Ratio Risk
Lean / Clean Bulk	+200 - 300	0.2 - 0.3 kg	Low (Best for Aesthetics)
Moderate Bulk	+400 - 500	0.4 - 0.5 kg	Moderate (Standard)
Aggressive / Dirty Bulk	+700 - 1000	0.7 - 1.0 kg	High (Max Strength)
Recomp	+0 (Maintenance)	~0 kg	Very Low (Slow Process)

Frequently Asked Questions

For 90% of people, a Lean Bulk (+250-300 kcal) is superior. The body has a limit on how much muscle it can synthesize in a day. Calories consumed above this limit will inevitably be stored as fat. Dirty Bulking is only recommended for true ectomorphs who are severely underweight and struggle to eat enough.

A target of 0.25% to 0.5% of body weight per week is ideal. For a 80kg male, that is roughly 0.2kg to 0.4kg per week. Faster gain usually indicates too much fat accumulation.

Actually, you might need slightly less protein per gram of body weight compared to cutting, because carbohydrates are protein-sparing. However, total absolute protein intake usually goes up because total food intake is higher.

Calculators are estimates. If the scale hasn't moved in 2 weeks, add another 200 calories to your daily target. Metabolic adaptation means your body may burn more energy as you eat more (NEAT), requiring further adjustments.