A macro calculator turns a calorie total and a percentage split into grams. It can help you understand the arithmetic behind a plan, but it cannot decide which calorie intake or split is appropriate for you.
Start with the inputs
Choose a calorie total and the percentages you want to explore for protein and fat. Carbohydrate uses the remaining percentage. Protein and fat together cannot exceed 100%, and the three shares should account for the entire total.
If you are uncertain about energy needs, our maintenance calorie calculator explains its estimation method. Treat that output as context, not an automatically prescribed intake.
Convert each share into grams
The general energy factors used here are 4 kcal per gram for protein and carbohydrate, and 9 kcal per gram for fat. The USDA Food and Nutrition Information Center explains energy and macronutrient information.
- Multiply the calorie total by the protein percentage, then divide by 4.
- Multiply the calorie total by the fat percentage, then divide by 9.
- Subtract those percentages from 100, then use the remainder for carbohydrate and divide its calories by 4.
Walk through one example
For an illustrative 2,000 kcal total with 25% protein and 30% fat, protein contributes 500 kcal, or 125 g. Fat contributes 600 kcal, or about 66.7 g. The remaining 45% is 900 kcal from carbohydrate, or 225 g. These inputs illustrate the calculation; they are not a recommended target.
Do not mistake neat numbers for a complete diet
The calculation does not assess food variety, fibre, micronutrients or suitability for a medical condition. Food labels may also differ slightly because of rounding and how energy is calculated. A meal does not need to match a mathematical split perfectly.
Try your own example in the macro calculator. For an easier planning routine, connect the numbers with meals you enjoy using our meal-planning guide.