Macro Calculator

Calories into protein, carbs, and fat

Nutrition labels allocate energy among macronutrients. This calculator starts from a daily calorie target and a chosen percent split for protein, carbohydrates, and fat, then converts each share into grams using standard Atwater factors used on most food labels:

• Protein ≈ 4 kcal per gram
• Carbohydrate ≈ 4 kcal per gram
• Fat ≈ 9 kcal per gram

Optional meals-per-day simply divides each gram target so you can plan portions. Alcohol energy and fibre adjustments are out of scope here.

Formulas

• kcal for a macro = daily kcal × (macro% ÷ 100)
• grams protein or carbs = that kcal ÷ 4
• grams fat = that kcal ÷ 9

Your three percentages should add to 100%. If they do not, reinterpret the split or adjust the inputs before trusting the grams.

Worked example

On 2,000 kcal with 30% protein / 40% carbs / 30% fat: protein = 600 kcal → 150 g; carbs = 800 kcal → 200 g; fat = 600 kcal → ~67 g. Across three meals that is about 50 g protein, 67 g carbs, and 22 g fat each if split evenly.

Choosing a split

Common patterns include higher-carb for endurance training, higher-protein during weight loss to protect lean mass, or more moderate balanced splits. This page does not prescribe a diet — it only turns your chosen percentages into grams. Pair with BMR & TDEE if you still need a calorie starting point.

Common mistakes

• Percentages that sum past 100%.
• Comparing “grams of carb” on one plan with “net carbs” on another without matching definitions.
• Assuming label calorie factors match a bomb calorimeter for every food.

FAQs

Where do calories come from?

Enter a target you already use, or estimate with BMR & TDEE.

Is sugar separate from carbs?

Sugar is part of carbohydrate grams unless a plan tracks it as a sub-limit.

Related: Protein, Nutrition, BMR & TDEE.