Macro Calculator
Macros — short for macronutrients — are the protein, carbohydrate, and fat that make up your calories. This macro calculator takes a daily calorie target and a percentage split and converts it into grams of each, using the standard Atwater energy factors: protein and carbohydrate provide 4 kcal per gram and fat provides 9. Set the percentages to match your goal (for example a higher-protein split for muscle retention while dieting), making sure they add up to 100%. The grams are an estimate to plan meals around, not a strict prescription.
Calculate
Default result: 150.0
Macro Calculator · Result
calculators.dev
Protein
2000 × 30 × 40 × 30
- Carbohydrate
- 200.0
- Fat
- 66.7
This calculator provides general estimates for educational purposes only and is not medical advice. Results are based on population formulas and may not reflect your individual circumstances. Consult a qualified healthcare professional before making changes to your diet, exercise, or health routine.
Reviewed by the calculators.dev team · Last updated 2026-06-23
Formula reviewed against USDA / Atwater general factors — protein 4, carbohydrate 4, fat 9 kcal per gram (standard metabolizable-energy values)
How to calculate
Enter your daily calorie target, then the percentage of calories you want from protein, carbohydrate, and fat. The three must total 100%. The calculator multiplies the calorie target by each percentage, then divides by that nutrient's calories per gram (4 for protein and carbs, 9 for fat). On 2,000 kcal at 30/40/30, that is 150 g protein, 200 g carbs, and 66.7 g fat. Adjust the split to suit your goal — many people set protein first (around 1.6–2.2 g per kg of body weight) and divide the rest between carbs and fat.
grams = (calories × percent ÷ 100) ÷ kcal_per_gram, where kcal_per_gram is 4 for protein, 4 for carbohydrate, and 9 for fat (the Atwater general factors). Variables: calories is the daily target, percent is that nutrient's share of calories, and the divisor is its energy density. The three percentages must sum to 100% or the split would not match the calorie total.
Example calculation
A 2,000 kcal target on a 30% protein / 40% carb / 30% fat split gives protein = 2000 × 0.30 ÷ 4 = 150 g, carbs = 2000 × 0.40 ÷ 4 = 200 g, and fat = 2000 × 0.30 ÷ 9 = 66.7 g. The three percentages must add up to 100%.
- proteinG
- 150.0 g
- carbG
- 200.0 g
- fatG
- 66.7 g
Assumptions
- Calories per gram use the standard Atwater factors (protein 4, carbohydrate 4, fat 9); real metabolizable energy varies slightly by food, but these are the universal planning values.
- The three percentages must add up to 100% so the macro grams exactly account for the calorie target.
- Alcohol (7 kcal/g) and fibre are not modelled separately — they fall outside this protein/carb/fat split.
Common mistakes
- Setting percentages that do not total 100%, which would leave calories unaccounted for. The calculator requires an exact 100% split.
- Forgetting that fat is more calorie-dense. The same percentage of calories yields far fewer grams of fat than carbs because fat has 9 kcal/g versus 4.
- Chasing an extreme split. Very low fat or very low carb percentages can be hard to sustain and may miss essential fats or fibre.
Frequently asked questions
What is a good macro split?
A balanced starting point is around 30% protein, 40% carbohydrate, and 30% fat, but the best split depends on your goal and preferences. Many people set protein first (about 1.6–2.2 g/kg of body weight) and divide the rest between carbs and fat.
How many grams of protein are in 30% of 2,000 calories?
2,000 × 0.30 = 600 calories from protein, and protein has 4 calories per gram, so 600 ÷ 4 = 150 g of protein per day.
Why does fat give fewer grams than carbs at the same percentage?
Fat is more energy-dense — 9 calories per gram versus 4 for carbs and protein. So an equal share of calories from fat works out to fewer grams.
Do I have to hit my macros exactly?
No. The grams are a planning target. Getting reasonably close most days — especially on protein — matters more than exactness. Treat the numbers as a guide, not a rule.