What Are Macros?
Macronutrients — or "macros" — are the three main categories of nutrients that provide calories: protein, carbohydrates, and fat. Protein provides 4 calories per gram and is essential for building and repairing muscle. Carbohydrates also provide 4 calories per gram and are the body's preferred energy source. Fat provides 9 calories per gram and supports hormone production, brain function, and fat-soluble vitamin absorption. Tracking macros allows you to optimise your diet not just for total calorie control, but for body composition and performance.
Our calculator uses the Mifflin-St Jeor equation — the most accurate BMR formula for most people — to estimate your Basal Metabolic Rate, multiplies by your activity factor to get TDEE (Total Daily Energy Expenditure), then adjusts calories and macro ratios according to your goal.
How to Use the Macro Calculator
- Enter your Age, Gender, Height, and Weight.
- Select your Activity Level — be honest; most people overestimate this.
- Choose your Goal: Lose Fat, Maintain, Build Muscle, or Aggressive Bulk.
- Results show your daily calories, protein, carbs, and fat targets.
- A per-meal breakdown (÷3 meals) makes hitting your targets straightforward.
Why Use Our Macro Calculator?
- Science-Based — Uses Mifflin-St Jeor BMR, the gold standard for TDEE estimation.
- Goal-Specific Macros — Different protein targets for fat loss, maintenance, and muscle building.
- Per-Meal Breakdown — See your targets split across 3 meals for practical meal planning.
- Live Calculation — Results update instantly as you change any input.
- 100% Free — No registration or subscription needed.
Frequently Asked Questions
Macros (macronutrients) are the three main calorie-providing nutrients: protein (4 cal/g), carbohydrates (4 cal/g), and fat (9 cal/g). Tracking macros lets you optimise your diet for specific goals — fat loss, muscle building, or performance — rather than just counting total calories. Unlike calorie counting alone, macro tracking ensures you are eating enough protein to preserve or build muscle.
Protein needs depend on your goal. For maintenance, 0.8g per pound of body weight is sufficient. For fat loss (to preserve muscle), 1.0g per pound is recommended. For muscle building or bulking, 1.0–1.2g per pound is optimal. Higher intakes (up to 1.5g/lb) are safe and may provide marginal additional benefits for advanced athletes. Space your protein intake evenly across 3–5 meals for best muscle protein synthesis.
Both matter, but macros give you more information. Counting only calories ensures you maintain a deficit or surplus, but tells you nothing about whether you are eating enough protein to preserve muscle or the right mix of carbs and fat for energy. Tracking macros automatically tracks calories too. For beginners, start with calories and protein targets; once those feel natural, add carbs and fat tracking.
A common general-purpose split is 30% protein / 40% carbs / 30% fat. For fat loss, a higher protein ratio (35–40%) preserves muscle. For endurance athletes, higher carb ratios (50–60%) support performance. For keto diets, fat makes up 65–75% of calories. Our calculator uses evidence-based targets: protein from body weight, fat at 25% of calories, and carbs filling the remainder.