Macro Calculator

This calculator uses the Mifflin-St Jeor equation — the most widely validated BMR formula for non-athletic adults — to estimate how many calories your body burns at complete rest. It then applies an activity multiplier based on your weekly exercise volume to calculate your Total Daily Energy Expenditure (TDEE), representing your true maintenance calorie level. A goal-specific calorie adjustment is then applied: a 500-calorie deficit for fat loss, no change for maintenance, or a 300-calorie surplus for muscle gain. Finally, your adjusted calorie target is divided among the three macronutrients using evidence-based ratios tailored to each goal. Weight loss uses higher protein (35%) to preserve muscle in a deficit. Muscle gain emphasizes carbohydrates (50%) to fuel training. Protein and carbohydrates each provide 4 kcal per gram, while fat provides 9 kcal per gram, which is why fat gram targets are proportionally smaller. Tracking macros rather than calories alone gives you a more complete nutritional picture and helps you meet body composition goals more effectively.

The Mifflin-St Jeor equation estimates your basal metabolic rate (BMR) — the calories your body needs at rest. For men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5. For women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161. Your total daily energy expenditure (TDEE) is then calculated by multiplying BMR by an activity factor ranging from 1.2 (sedentary) to 1.9 (super active). A calorie adjustment is applied based on your goal: subtract 500 kcal for weight loss, add 300 kcal for weight gain, or keep TDEE for maintenance. Macros are then split using goal-specific ratios: weight loss is 35% protein, 30% fat, 35% carbs; maintenance is 30/30/40; muscle gain is 25/25/50. Protein and carbs yield 4 kcal/g; fat yields 9 kcal/g.