Macro Calculator: Calories, Protein, Carbs & Fat
Convert a calorie total and your chosen macro percentages to grams of protein, carbohydrates and fat, or calculate macro energy from grams. This tool performs a conversion; it does not determine your calorie needs, prescribe a macro split or recommend a weight-loss diet.
Convert calorie percentages to grams
For each macro, calculate its calories first: macro kcal = total kcal x percentage / 100. Then divide protein or carbohydrate calories by 4, and fat calories by 9.
For Total calories (kcal) 2000, Protein (%) 25, Carbohydrates (%) 50 and Fat (%) 25, the result is 125.00 g protein, 250.00 g carbohydrates and 55.56 g fat. The calorie split is 500, 1000 and 500 kcal. This split is an arithmetic example, not a recommendation.
Calculate calories from macro grams
Select Grams to calories and percentages. Formula: macro energy = protein grams x 4 + carbohydrate grams x 4 + fat grams x 9. For Protein (g) 50, Carbohydrates (g) 200 and Fat (g) 60, the total is 1540.00 kcal.
Energy shares are each macro's calories divided by the total macro calories. In that example, protein contributes 200 kcal, carbohydrates 800 kcal and fat 540 kcal. The percentages describe energy, not grams or food weight. If all gram entries are zero, total energy is zero and energy percentages are undefined.
Why the percentage total must be 100%
A percentage-based split distributes the whole entered calorie total across three macros. This tool rejects totals above or below 100%, instead of silently normalizing them. A zero share for one macro is accepted mathematically, but acceptance is not a recommendation to omit a nutrient.
Inputs support up to two decimal places. Each percentage must be between 0 and 100. The calorie total must be greater than zero and at most 100,000; gram inputs can be 0 to 10,000 each. Those are software limits, not appropriate intake ranges. Changing the calculation method clears entries to avoid interpreting percentages as grams.
Food labels and general energy factors
The 4/4/9 factors are general approximations. Food-label calculations may use more specific factors or different treatment of fiber, sugar alcohols, alcohol and other components. Rounding and labeling rules can also cause a difference between this macro total and a package's stated calories. Do not add the difference automatically to one macro.
For context on energy calculations and allowed factors, see 21 CFR 101.9, nutrition labeling of food. This calculator does not verify that a recipe or food label is compliant with labeling requirements.
Calorie needs, weight goals and privacy
If you need a separate estimate of resting or daily maintenance energy, use the Calorie Calculator. A mathematical macro split does not establish an appropriate calorie intake, guarantee weight loss or account for medical conditions, pregnancy, breastfeeding or children's needs. Seek individualized guidance where needed.
This tool does not save or transmit your entries. Calculations happen locally in the browser; the hosting website may use separate analytics or other services under its privacy policy.
Worked examples and step-by-step guide
Read How to Calculate Macros: Calories, Percentages and Grams for both calculation methods, energy shares and rounding checks.
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