Why muscle gain needs more protein than maintenance
Building new muscle tissue is a constant process of breaking down muscle protein through training and rebuilding it slightly bigger and stronger — a process called muscle protein synthesis. That rebuilding requires a steady supply of amino acids from food. Without enough protein, your body simply doesn't have the raw material to build new tissue, no matter how hard or consistently you train. That's why this calculator uses the highest baseline protein-per-kg figure of any goal for muscle gain.
Training intensity matters as much as the number on the scale
Someone doing regular strength training or high-performance training gets more benefit from additional protein than someone training lightly, because harder training creates more muscle breakdown that needs repairing. This calculator adjusts your target upward for strength training or high-performance activity levels — select the one that best matches your actual training, not your goal, for the most accurate number.
Building muscle usually means eating slightly more overall
If you enter a goal weight above your current weight, this calculator nudges your reference weight up — halfway toward your goal, capped at 10% above your current weight — since a body that's actively gaining muscle needs to be fed slightly ahead of where it is today, not exactly at today's weight.
Best protein sources for muscle gain
Chicken breast, lean beef, eggs, Greek yoghurt, cottage cheese and salmon all provide a complete amino acid profile in a reasonably calorie-efficient package — useful since building muscle also usually means eating in a slight calorie surplus. See 40g, 50g and 60g protein meal ideas for meals sized around a muscle-building target. If you use a shake to top up, our protein powder comparison covers which types suit muscle gain.
FAQs
How much protein do I need to build muscle?
Most people building muscle need somewhere around 2.0–2.4g of protein per kilogram of bodyweight per day, depending on training intensity and age — use the calculator above for a number based on your specific details.
Can I build muscle without eating more calories overall?
It's possible in some circumstances (especially for beginners or when returning to training), but building muscle is generally easier in a slight calorie surplus. Protein alone won't build muscle without enough total energy to support the process.
Does age affect how much protein I need to build muscle?
Yes — older adults need more protein per kilogram to build or even maintain the same amount of muscle, since the body responds less efficiently to protein intake as it ages. This calculator accounts for that automatically based on the age you enter.