HEALTH · MACRONUTRIENT
Macronutrient Calculator
Convert a daily calorie target into protein, carbohydrate, and fat gram targets using a customisable macro split.
About This Calculator
Once you know your daily calorie target (from a TDEE or BMR calculator), this tool converts it into grams of protein, carbohydrates, and fat based on the percentage split you choose. The default 20/50/30 split aligns with the USDA Dietary Guidelines 2020–2025 for a balanced diet.
How It Works
Enter your daily calorie target and the percentages you want from protein, carbohydrates, and fat (they must sum to 100%). The calculator divides the calorie share of each macro by its energy density: protein and carbohydrates yield 4 kcal per gram; fat yields 9 kcal per gram.
The Formula
Protein (g) = cal × P% / 400 Carbs (g) = cal × C% / 400 Fat (g) = cal × F% / 900
- cal
- daily calorie target (kcal)
- P%, C%, F%
- percentage of calories from protein, carbs, fat
Frequently Asked Questions
- What is a good macro split?
- The USDA recommends 45–65% carbohydrates, 10–35% protein, and 20–35% fat for most adults. Athletes, people with specific health goals, or those on therapeutic diets may use different splits — a registered dietitian can advise.
- Why do protein and carbs use 4 kcal/g but fat uses 9 kcal/g?
- These are the Atwater factors — the approximate metabolisable energy per gram for each macronutrient, derived from calorimetry experiments. Fat is more energy-dense because it is hydrophobic and more chemically reduced.
- Does this replace a dietitian?
- No. This tool does arithmetic on your inputs and does not account for your health history, medical conditions, activity level, or dietary needs. A registered dietitian can build a personalised nutrition plan.