Muscle Building Macro Calculator
Determine your daily protein target for building muscle from your body weight and training intensity, using the ISSN range of 1.6–2.2 g per kg (0.7–1.0 g per lb). Ideal for lifters setting up a structured bulking diet.
Last updated: September 2026
Formula below · 3 sources (dietaryguidelines.gov, acsm.org, eatright.org) · Updated Sep 2026
Compare with similar
About this calculator
Macronutrient planning for muscle building starts with protein, which provides the amino acids needed for muscle protein synthesis (MPS). This calculator returns your daily protein target: protein (g) = round(bodyWeight_lb × 0.453592 × factor), with the factor 2.2 g/kg for high-intensity training, 1.8 g/kg for moderate and 1.6 g/kg for low intensity (about 1.0, 0.82 and 0.73 g per pound). These follow ISSN guidance of 1.6–2.2 g of protein per kilogram (roughly 0.7–1.0 g/lb) for strength athletes. Once protein is set, fill the rest of your calories with carbohydrates (4 kcal/g), which fuel training and glycogen replenishment, and dietary fat (9 kcal/g, at least about 20% of calories), which supports hormonal health.
How to use
Say you weigh 180 lbs (81.6 kg) and train at high intensity. Daily protein target = round(180 × 0.453592 × 2.2) = 180 g — about 1.0 g per pound. Moderate training gives round(81.65 × 1.8) = 147 g and low intensity round(81.65 × 1.6) = 131 g. Spread it across 4–5 meals and fit carbs and fat around your own daily calorie target.
Frequently asked questions
How much protein do I need per day to build muscle effectively?
Current evidence supports 1.6–2.2 g of protein per kilogram of body weight per day for maximizing muscle protein synthesis in resistance-trained individuals, equivalent to roughly 0.7–1.0 g per pound. Higher-intensity training and larger calorie deficits push protein needs toward the upper end of this range. Spreading protein intake across 3–5 meals of 30–50 g each optimizes leucine-driven MPS throughout the day. This calculator uses training intensity as the primary driver to set your protein target within that validated range.
What is the best macro ratio for muscle building while minimizing fat gain?
There is no single universal macro ratio, but a common evidence-based starting point for a lean bulk is roughly 30–35% protein, 40–50% carbohydrates, and 20–30% fat. Carbohydrates are prioritized because they replenish muscle glycogen, support training intensity, and are protein-sparing. Fat should not drop below ~20% of calories to maintain testosterone and other anabolic hormones. Individual carb tolerance — influenced by insulin sensitivity and activity level — should guide the exact carb-to-fat split.
Should I adjust my macros on rest days vs training days when bulking?
Carbohydrate intake is often cycled between training and rest days because glycogen demand is highest around workouts. On training days, higher carb intake supports performance and post-workout recovery; on rest days, slightly lower carbs (replaced by fat) can reduce unnecessary caloric surplus. Protein should remain consistently high every day regardless of training status, since muscle protein synthesis is elevated for up to 48 hours after a session. A simple approach is to keep protein constant, keep fat constant, and modulate only carbohydrates by 50–100 g between training and rest days.