Macro Calculator

How Your Macros Are Calculated

This calculator first estimates your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation, the formula most commonly recommended by dietitians for its accuracy across a wide range of body types: for men, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5; for women, subtract 161 instead of adding 5. Your BMR is then multiplied by an activity factor to estimate your Total Daily Energy Expenditure (TDEE) — your maintenance calories. Your goal shifts that number by a standard ±15-20% for weight loss or gain, and the result is split into protein, carbohydrate, and fat grams using 4 calories per gram for protein and carbs and 9 calories per gram for fat.

Why Protein Targets Matter More Than the Exact Split

The three preset splits offered here (balanced, lower-carb, higher-carb) are common starting points, not rigid rules — total calories and adequate protein intake matter far more for body composition than the exact carb-to-fat ratio. If you're trying to preserve or build muscle while losing fat, prioritize hitting your protein target consistently; you can use the protein calculator to sanity-check that number against your body weight and activity level.

Adjust Based on Real-World Results

These numbers are a well-reasoned starting estimate, not a guarantee — actual metabolism varies by 10% or more between individuals with identical stats. Track your weight and how you feel for 2-3 weeks, then adjust calories up or down by 100-200 if progress stalls. For a broader view of your daily energy needs and how activity level changes them, see the TDEE calculator. This tool provides educational estimates only and isn't a substitute for personalized advice from a doctor or registered dietitian, especially if you have a medical condition affecting your metabolism or nutrition needs.