Macro & Calorie Calculator — educational

BMR (Basal Metabolic Rate) is the energy you'd burn if you stayed in bed all day — it powers breathing, circulation, cell production, and brain function.

TDEE (Total Daily Energy Expenditure) multiplies BMR by an activity factor: 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 active, 1.9 very active, 2.05 athlete.

Goal applies a percentage to TDEE: a 20 % cut means eating 80 % of TDEE, a 10 % bulk means eating 110 %. A pound of fat is roughly 3,500 kcal, so a 500 kcal / day deficit works out to about a pound a week — but water, glycogen, and individual variation make the actual scale number bounce around.

Macros split the daily target into protein, fat, and carbs. Protein is set in grams per kilogram of body weight (1.6 g/kg is a reasonable floor for active adults); fat is set as a percentage of total kcal; carbs are whatever's left over.

What the calculator doesn't capture: muscle mass, bone density, hormonal conditions, thyroid function, medications, gut microbiome, sleep quality, training intensity, and the fact that lean people often over-eat and overweight people often under-eat relative to their reported intake. The Mifflin–St Jeor equation was derived from mostly North-American adults aged 19-78; outside that range, accuracy drops.

Use this to learn the math, sanity-check a meal plan, and have a sensible starting point. For personal guidance, talk to a registered dietitian — especially if you're pregnant, an athlete, managing a condition, or significantly under- or overweight.