A macronutrient (macro) calculator determines your optimal daily intake of protein, carbohydrates, and fats based on your body composition, activity level, and specific goal — fat loss, muscle gain, or maintenance. Unlike generic calorie-only approaches, macro tracking ensures that your calorie target is composed of the right balance of nutrients to support your training adaptations and body composition goals.

This calculator first derives your BMR (Basal Metabolic Rate) using the Mifflin-St Jeor equation — the most accurate validated formula for the general population — then multiplies by an activity factor to get your TDEE (Total Daily Energy Expenditure). A goal-specific calorie offset is then applied (deficit for fat loss, surplus for muscle gain), and macros are distributed in ratios validated by sports nutrition research: higher protein in deficit phases to preserve muscle, higher carbohydrates in surplus phases to fuel training and glycogen storage.

Macro ratios are not one-size-fits-all. The splits provided are evidence-based starting points from the International Society of Sports Nutrition (ISSN) and the Academy of Nutrition and Dietetics. Track your results for 2–3 weeks, monitor weight and performance, and adjust. Real-world tracking is more reliable than any formula for finding your personal optimal intake.