A surplus of 250-500 calories above your TDEE is optimal for muscle gain. A 250-calorie surplus (lean bulk) minimizes fat gain while still supporting muscle growth. Larger surpluses (500+) build muscle faster but with more accompanying fat gain.

Research supports 0.7-1.0 grams of protein per pound of body weight for muscle building. This calculator uses 0.7g/lb as a baseline. Active lifters in a surplus may benefit from the higher end of this range (1.0g/lb).

Beginners, those returning after a break, and overweight individuals can build some muscle in a deficit. However, a moderate caloric surplus is significantly more effective for muscle growth, especially for intermediate and advanced lifters.