Health📅 18 March 2025⏱ 6 min read
How to Calculate Macros for Fat Loss, Muscle Building or Maintenance
Tracking macros — protein, carbohydrates, and fat — gives you much more control over your body composition than calorie counting alone. Here's how to calculate your targets from scratch.
JW
James WhitfieldPersonal Finance & Maths WriterJames has written about personal finance, health metrics, and everyday mathematics for over six years. He holds a BSc in Mathematics from the University of Leeds.
Calories determine whether you lose or gain weight. Macros — the ratio of protein, carbohydrates, and fat — determine what kind of weight you gain or lose. Here's how to calculate the right split for your goal.
Step 1: Find Your TDEE
Macro targets are built on top of your calorie target, which is built on your TDEE (Total Daily Energy Expenditure). Calculate this first using your age, sex, weight, height, and activity level. Then adjust:
- Fat loss: TDEE minus 300–500 calories
- Muscle building (lean bulk): TDEE plus 150–300 calories
- Maintenance / body recomposition: TDEE calories
Step 2: Set Protein First
Protein is the highest priority macro because it preserves (and builds) muscle and is the most satiating macronutrient. Set it before carbs and fat.
Fat loss: 1.8–2.2g per kg of bodyweight
Muscle building: 1.6–2.2g per kg of bodyweight
Maintenance: 1.4–1.8g per kg of bodyweight
Protein = 4 calories per gram
Example: 75kg person in fat loss phase
Protein = 75 × 2.0 = 150g = 600 calories
Step 3: Set Fat
Dietary fat is essential for hormone production, joint health, and absorption of fat-soluble vitamins (A, D, E, K). Don't go too low.
Minimum: 0.8g per kg of bodyweight
Typical range: 0.8–1.2g per kg
Fat = 9 calories per gram
Example: 75kg person
Fat = 75 × 1.0 = 75g = 675 calories
Step 4: Fill Remaining Calories With Carbs
Carbohydrates are the body's preferred fuel for exercise and brain function. After setting protein and fat, fill the remaining calorie budget with carbs.
Carb calories = Total calorie target − Protein calories − Fat calories
Carbs (g) = Carb calories ÷ 4
Example: 1,600 calorie target
Protein: 600 cal | Fat: 675 cal
Carb calories = 1,600 − 600 − 675 = 325 cal
Carbs = 325 ÷ 4 = 81g
Full Example: 75kg Person, Fat Loss Goal
MacroAmountCalories
Protein150g600 kcal (37.5%)
Fat75g675 kcal (42.2%)
Carbohydrates81g325 kcal (20.3%)
Total—1,600 kcal
Common Macro Splits by Goal
GoalProtein %Fat %Carbs %
Fat loss35–40%30–35%25–35%
Lean bulk25–30%25–30%40–50%
Endurance athlete20–25%20–25%50–60%
Ketogenic20–25%65–75%5–10%
Do You Need to Track Macros?
Not everyone needs to track macros precisely. For general health, hitting your protein target and staying within your calorie range is usually sufficient. Detailed macro tracking is most valuable for:
- Athletes optimising body composition
- People who've plateaued despite tracking calories
- Those who want to understand exactly where their nutrition is going
Most people find tracking useful for 4–6 weeks to build food awareness, then can maintain results without ongoing tracking once they have a calibrated sense of their typical diet.