What This Calculator Measures

The Bulking Calorie Calculator determines your calorie targets for gaining muscle mass at three different surplus levels. Choosing the right surplus size is the key to gaining muscle efficiently without excessive fat gain.

Diagram showing how the Bulking Calorie Calculator works — How the Bulking Calorie Calculator works

How It Works

The calculator first computes your TDEE using the Mifflin-St Jeor equation, then adds a caloric surplus:

Bulk Type	Surplus	Expected Weekly Gain	Best For
Lean bulk	+250 kcal	~0.12 kg/week	Intermediate/advanced lifters, minimizing fat gain
Standard bulk	+500 kcal	~0.25 kg/week	Most lifters, balanced approach
Aggressive bulk	+750 kcal	~0.37 kg/week	Beginners, hardgainers, underweight individuals

Choosing Your Surplus

•**Lean bulk (+250):** Best for experienced lifters who gain muscle slowly and want to minimize fat gain. Requires precise tracking.

•**Standard bulk (+500):** The most common recommendation. Provides enough surplus for muscle growth with manageable fat gain.

•**Aggressive bulk (+750):** Reserved for hardgainers, beginners (who have the highest potential for rapid muscle gain), or underweight individuals.

Monitoring Progress

Weigh yourself daily and track the weekly average. If you are gaining faster than expected, reduce calories by 100-200. If not gaining at all after 2-3 weeks, increase by the same amount.

Limitations

•Muscle gain rates are limited by biology (roughly 0.5-1 kg per month for intermediates). Excess calories beyond what supports muscle growth will be stored as fat.

•TDEE calculations are estimates. Adjust based on real-world scale trends.

•Genetic factors, training program quality, sleep, and stress all affect how effectively surplus calories are partitioned toward muscle growth.