How Macronutrient Targets Are Calculated

Summary

Macronutrient (“macro”) calculation splits your daily calorie target into grams of protein, carbohydrates, and fat. The split depends on your goal (weight loss, maintenance, or muscle gain), activity level, and body composition. The calculator uses your TDEE as the starting point and applies evidence-based ratios to determine how many grams of each macro you should eat daily.

How it works

Step 1: Determine calories

Start from your TDEE (Total Daily Energy Expenditure), then adjust based on goal:

• Fat loss: TDEE minus 300-500 calories
• Maintenance: TDEE
• Muscle gain: TDEE plus 200-500 calories

Step 2: Set protein

Protein is set first because it is the most important macro for body composition:

Step 3: Set fat

Fat is essential for hormone function and should not drop too low:

• Minimum: 0.5 g/kg body weight (approximately 20% of calories)
• Typical: 25-35% of total calories
• Each gram of fat = 9 calories

Step 4: Fill remaining with carbohydrates

After protein and fat are set, the remaining calories come from carbohydrates:

• Each gram of carbohydrate = 4 calories
• Each gram of protein = 4 calories

Carb grams = (Total calories - Protein calories - Fat calories) / 4

Worked example

80 kg male, moderately active, fat loss goal. TDEE: 2,600 kcal, Target: 2,100 kcal

1. Protein: 80 kg x 2.0 g/kg = 160 g (640 kcal)
2. Fat: 30% of 2,100 = 630 kcal = 70 g
3. Carbs: (2,100 - 640 - 630) / 4 = 830 / 4 = 208 g

Daily targets: 160g protein, 208g carbs, 70g fat = 2,100 kcal

Common macro splits

Inputs explained

• Body weight — used for protein calculation (per-kg basis)
• Goal — fat loss, maintenance, or muscle gain
• TDEE or calorie target — your daily energy needs
• Activity level — influences protein needs
• Preference — high-carb, moderate, or low-carb approach

Outputs explained

• Protein, carbs, fat in grams — daily targets for each macro
• Calorie breakdown — percentage of calories from each macro
• Per-meal targets — if you specify number of meals per day

Assumptions & limitations

• Macro calculations provide a starting point. Individual response varies and adjustments based on progress are essential.
• Fibre is a carbohydrate but is not fully digested. The calculator does not separately track fibre.
• Alcohol provides 7 kcal/g and is not classified as a macronutrient but contributes to total calories.
• Higher protein intakes (2.2+ g/kg) are safe for healthy individuals but may need adjustment for those with kidney conditions.
• The calculator uses body weight, not lean mass. For very overweight individuals, using a target or ideal body weight for protein calculation may be more appropriate.