Macro Calculator
Daily protein, carb and fat targets for your goal and diet.
Formula
About this calculator
A macro calculator goes one step beyond counting calories by telling you how those calories should be divided among the three macronutrients — protein, carbohydrates and fat. This breakdown, popular in flexible dieting or "IIFYM" (if it fits your macros), is what shapes body composition: two diets with identical calories can produce very different results depending on their protein and carb balance.
The tool first calculates your daily calorie target the same way a good calorie calculator does — the Mifflin-St Jeor BMR multiplied by your activity level, then adjusted for whether you want to lose, maintain or gain. It then splits those calories according to the diet ratio you choose, whether balanced, high-protein, low-carb or ketogenic.
Converting calories to grams uses the Atwater energy values that are standard on every nutrition label: protein and carbohydrates each provide four calories per gram, while fat provides nine. That is why a low-carb or keto split shifts so many grams toward fat — fat is more than twice as calorie-dense, so fewer grams cover a larger share of energy.
Protein is usually the macro worth prioritising, since it preserves muscle during a diet and keeps you full, which is why the high-protein and low-carb presets push it higher. Use these targets as a starting framework, track your intake for a few weeks, and adjust based on real-world progress and how you feel rather than treating the numbers as fixed.
Frequently asked questions
What are macros?
The three macronutrients that provide energy: protein, carbohydrates and fat. A macro calculator splits your daily calories among them based on your goal and chosen diet.
How are grams calculated from calories?
Using standard Atwater values — 4 calories per gram for protein and carbs, 9 for fat. The calculator applies your chosen percentage split, then converts each share to grams.
How much protein should I eat?
The presets range from 30% to 40% of calories. Higher protein helps preserve muscle and control appetite when dieting, which is why the high-protein and low-carb options raise it.
Which macro split is best?
There's no single best split; it depends on your goals and preferences. A balanced split suits most people, while low-carb or keto favors fat and appeals to some — consistency matters more than the exact ratio.
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⚠️ Macro targets are general guidance, not medical or dietary advice. Individual needs vary; consult a doctor or dietitian before major diet changes.