Macro Calculator — Protein, Carbs and Fat for Your Goal
This macro calculator sets protein first based on your body weight, sets fat at 25 percent of your calories, then fills whatever is left with carbohydrate. For fat loss it uses 2.2 g of protein per kg of body weight; for maintenance 1.6 g/kg; for muscle gain 1.8 g/kg. Total calories matter more than the exact split, so hit your protein and calorie targets first and adjust the rest to taste.
What is macro calculator?
Macronutrients are the three calorie-bearing components of food: protein and carbohydrate at 4 kcal per gram, and fat at 9 kcal per gram. Alcohol, at 7 kcal per gram, is sometimes called a fourth macro.
Protein is the macro worth managing deliberately. It preserves muscle during weight loss, has the highest thermic effect of the three — you burn roughly 20 to 30 percent of its calories just digesting it — and it is the most filling.
Carbohydrate and fat are largely interchangeable for energy. Where they are not interchangeable is performance and preference: very low carbohydrate intake impairs high-intensity work, and very low fat intake affects hormone production.
How your macros are calculated
First your TDEE is estimated with Mifflin-St Jeor. That figure is adjusted by goal: minus 500 kcal for fat loss, plus 400 for lean gain. Protein is then fixed by body weight rather than by percentage, because protein needs scale with lean mass, not with calories. Fat is set at 25 percent of calories to keep hormone function and absorption of fat-soluble vitamins adequate. Carbohydrate takes the remainder.
Protein (g) = body weight (kg) × target g/kg
2.2 g/kg cutting · 1.8 g/kg bulking · 1.6 g/kg maintaining
Fat (g) = total kcal × 0.25 ÷ 9
Carbs (g) = [total kcal − (protein × 4) − (fat × 9)] ÷ 4Source: Based on ISSN and ACSM position statements on protein intake.
How to use this calculator
- Enter your stats and pick the activity level that matches your actual week.
- Choose your goal: lose fat, maintain, or build muscle.
- Note the protein target first — this is the number to protect every day.
- Split the remainder between carbs and fat according to how you train and what you enjoy eating.
- Revisit after any weight change of 5 kg or more.
Frequently asked questions
How much protein do I actually need?
For people who train, roughly 1.6 to 2.2 grams per kilogram of body weight per day. Going higher is safe for healthy adults but adds little. Sedentary people need about 0.8 to 1.2 g/kg.
Is there an ideal macro split?
No single split is superior for fat loss when calories and protein are matched. Studies consistently find that adherence — which diet you can actually follow — predicts results better than the ratio.
Should I cut carbs or fat to lose weight?
Whichever you find easier to sustain. Low-carb diets tend to produce faster early scale drops from glycogen and water loss, but long-term fat loss tracks total calorie intake.
Do I need to hit my macros exactly every day?
No. Think in weekly totals. A day at 120 g of protein when your target is 150 g is fine if the rest of the week averages out. Consistency over weeks beats daily precision.
Why is my carbohydrate target so high or so low?
Carbohydrate absorbs the remainder after protein and fat are set. If you cut calories hard while keeping protein high, carbs shrink a lot — this is normal, not an error.
Related calculators
- Calorie Calculator — Free calorie calculator using the Mifflin-St Jeor equation. See how many calories you should eat to maintain, lose or gain weight, plus your BMR.
- Protein Intake Calculator — Calculate your daily protein target in grams based on body weight and activity level, with per-meal breakdowns for 3 or 4 meals.
- BMR Calculator — Calculate your basal metabolic rate with the Mifflin-St Jeor equation, or use Katch-McArdle if you know your body fat percentage.
These figures are estimates from population formulas, not medical advice. Individual needs vary. If you are pregnant, managing a medical condition, or under 18, talk to a doctor before changing your diet.