Free Tool

Macro Calculator for Muscle Gain

Calculate your daily calories and macro targets for building lean muscle. Get a structured caloric surplus designed to maximize muscle growth while minimizing excess fat gain.

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How this muscle gain calculator works

Building muscle requires a caloric surplus: eating more calories than you burn. This calculator estimates your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation, then adds a moderate surplus of approximately 550 calories per day. This targets a weight gain rate of about 0.5 kg (1 lb) per week, which research suggests is close to the upper limit of lean tissue gain for most natural trainees when combined with a progressive resistance training program.

Protein is set at 1.8 grams per kilogram of body weight, which is within the evidence-based range for maximizing muscle protein synthesis (1.6-2.2 g/kg). Fat provides 25% of total calories for hormone support, and the remaining calories come from carbohydrates, which fuel training performance and support recovery.

Keys to a successful muscle-building phase

  • Progressive overload: Gradually increase weight, reps, or volume over time. Without a training stimulus, extra calories are stored as fat, not muscle.
  • Moderate surplus: A surplus of 300-600 kcal above TDEE is sufficient. Larger surpluses do not accelerate muscle growth but do increase fat gain.
  • Distribute protein: Aim for 4-5 protein-rich meals spread throughout the day, each containing 25-40g of protein, to maximize muscle protein synthesis.
  • Prioritize carbs around training: Place the majority of your carbohydrate intake before and after workouts to fuel performance and replenish glycogen.
  • Monitor progress: Track body weight weekly. If gaining more than 0.5-1% of body weight per week, reduce calories slightly to limit fat accumulation.

How long should a bulking phase last?

Most coaches recommend bulking phases of 3-6 months, followed by a maintenance phase or mini-cut. This allows enough time to accumulate meaningful muscle tissue without gaining excessive body fat. If your body fat reaches a level where you are uncomfortable or exceeds roughly 20% for men or 30% for women, it may be time to transition to a cutting phase.

Other goals

Ready to cut? Use the weight loss macro calculator for a structured deficit with high protein to preserve muscle. Want to maintain your current physique? Try the maintenance macro calculator to find your sustaining calorie level.