Estimate your basal metabolic rate, the number of calories your body would burn in a day at complete rest just to keep essential functions running like breathing, circulation and cell repair. Enter your age, sex, height and weight, and the calculator uses the Mifflin-St Jeor equation, widely regarded as one of the most accurate predictive formulas for everyday use. Your BMR is the foundation for any calorie plan: your total daily needs are your BMR scaled up by how active you are. Knowing this baseline helps you understand why very low-calorie diets can be counterproductive. This is an estimate for general guidance, not a substitute for professional advice, and everything is computed locally in your browser.