Calorie & Macro Calculator for Muscle Gain
Build muscle, not just weight. This calculator sets a lean-bulk surplus and a protein-forward macro split, then shows exactly how many grams of protein, carbs, and fat to eat each day.
Your details
1.6–2.2 g/kg supports muscle growth for most lifters.
Protein-forward macros
Protein set by bodyweight, fat at 25%, carbs fuel the rest.
How your surplus is built
Building muscle needs two things: a calorie surplus to supply the energy, and enough protein to build new tissue. This calculator handles both. It adds a controlled surplus to your maintenance calories, then splits those calories into macros with protein set by your bodyweight, fat held at a healthy 25%, and carbohydrates fuelling the rest of your training. The donut updates live as you tune your protein target and surplus.
Why protein leads the way for muscle gain
Protein provides the amino acids your body uses to repair and grow muscle after training. Research consistently points to roughly 1.6–2.2 grams of protein per kilogram of bodyweight as the range that maximises muscle growth for people lifting weights. This tool lets you set your protein target directly in grams per kilogram, calculates the grams for your weight, and fills the rest of your calories with carbs and fat.
Carbohydrates matter too — they fuel hard training sessions and help spare protein for muscle-building rather than energy. That's why this calculator keeps carbs generous rather than cutting them, unlike a fat-loss macro split.
Combining surplus and macros
A lean bulk works best with a modest surplus — enough to grow, but not so much that you add unnecessary fat. Pair the 250–500 calorie surplus with your protein target and consistent resistance training, and you give your body everything it needs to build muscle at close to its natural maximum rate.
The Energy Flow diagram shows how your surplus is built from BMR and activity, while the macro donut breaks your daily calories into grams. If you only want the calorie target without the macro detail, our weight-gain calculator covers that.
Frequently Asked Questions
Aim for about 1.6–2.2 grams of protein per kilogram of bodyweight per day. The calculator lets you set this directly and converts it to grams and calories for your weight.
Protein driven by bodyweight, fat around 25% of calories for hormone health, and the remaining calories from carbohydrates to fuel training. This calculator applies exactly that split on top of a lean-bulk surplus.
A 250–500 calorie surplus is ideal. It supplies enough energy to build muscle while limiting fat gain. Larger surpluses mostly add fat, since muscle can only be built so quickly.
They help a lot. Carbohydrates fuel intense training and spare protein for muscle repair rather than energy, which is why this calculator keeps carbs generous rather than restricting them.
Recalculate every few weeks as your weight changes, since both your maintenance calories and your protein target scale with bodyweight.
These results are estimates for general educational purposes only and are not medical or nutritional advice. Individual needs vary. Consult a qualified healthcare professional or registered dietitian before making significant changes to your diet, especially if you are pregnant, breastfeeding, under 18, or have a medical condition.