Macro Calculator

The calculator first finds your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation, then multiplies it by an activity factor (1.2 for sedentary up to 1.9 for athletes) to estimate Total Daily Energy Expenditure (TDEE) — the calories you burn in a typical day including activity.

Protein and carbs both provide 4 calories per gram, while fat provides 9 calories per gram — the calculator takes your chosen percentage split of total calories for each macro, then divides by that macro's caloric density to get the target grams.

The presets are common patterns, not universal rules: 40/30/30 is a balanced general-fitness split, 30/40/30 favors slightly more carbs (useful for endurance training), and 40/20/40 is a lower-carb pattern. None is inherently "correct" — the right split depends on your specific training goals and how your body responds, ideally in consultation with a nutrition professional.

No — it calculates your maintenance TDEE (calories to keep your current weight roughly stable) and splits that number into macros. For weight loss or gain, you'd apply a calorie deficit or surplus to the TDEE number first, then still use the same macro percentage split for the adjusted total.