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Splitting calories into protein, carbs and fat
A macro calculator turns a daily calorie target into grams of protein, carbohydrate and fat. Total calories decide whether you gain or lose weight; the split between macros decides how much of that change is muscle rather than fat, and how well you can sustain the diet. Protein is anchored to your body weight, and the rest of the calories are divided from there.
How to use the Macro Calculator
- Enter your Weight (kg) — protein scales from this.
- Enter your Target Calories (kcal) for the day.
- Read grams of protein, carbohydrate and fat.
- Use our BMR calculator first if you do not know your calorie target.
Formula and a worked example
Protein ≈ 2 g per kg body weight · Fat ≈ 25% of calories · Carbohydrate = the remainder
Protein 4 kcal/g · Carbohydrate 4 kcal/g · Fat 9 kcal/g
Fat carries more than twice the calories per gram of the other two, so small changes in fat grams move total calories a lot. Protein is set per kilogram of body weight rather than as a percentage, because muscle retention depends on absolute intake.
Worked example
An 80 kg person eating 2,200 kcal: protein 160 g (640 kcal), fat 61 g (550 kcal), leaving 1,010 kcal for carbohydrate — about 253 g.
Frequently asked questions
How much protein do I actually need?
Around 1.6–2.2 g per kilogram if you train and want to keep muscle. Sedentary adults need far less, roughly 0.8 g per kilogram.
Do macros matter more than calories?
No. Calories decide the direction of weight change; macros decide the quality of it and how easy the diet is to stick to.
Should I lower carbs to lose fat?
Not necessarily. Low-carb diets work for some people because they reduce appetite, but at equal calories and protein the fat loss is similar.
How exact do I need to be?
Getting within about ten grams of each target daily is plenty. Weekly consistency beats daily precision.
Related calculators
Other tools people use alongside the macro calculator.