Resting Calorie Burn Calculator

Basal Metabolic Rate (BMR) — sometimes called resting metabolic rate (RMR) — is the number of calories your body burns at complete rest to maintain essential functions: breathing, circulation, cell production, body temperature regulation, and organ function. It typically accounts for 60–75% of total daily energy expenditure in sedentary individuals.

BMR is resting calorie burn — the minimum energy needed to survive. TDEE (Total Daily Energy Expenditure) adds the energy cost of physical activity, digestion, and non-exercise movement. Eating at TDEE maintains weight; eating below it creates a deficit for weight loss; eating above it supports weight gain.

The Mifflin-St Jeor equation (1990) is currently recommended by the Academy of Nutrition and Dietetics as the most accurate for most adults. The Katch-McArdle formula is more accurate for people who know their body fat percentage, as it uses lean body mass rather than total weight. The Harris-Benedict equation (revised 1984) tends to run slightly higher and may overestimate in some groups.

BMR is higher with: greater muscle mass, younger age, taller and heavier frame, male sex (on average), and in some cases fever or pregnancy. BMR is lower with: higher body fat percentage relative to lean mass, older age, crash dieting or prolonged caloric restriction (adaptive thermogenesis), hypothyroidism, and significant muscle loss.

A common approach is to eat 500 calories below TDEE per day, which creates approximately 0.5 kg (1 lb) of fat loss per week. A 250-calorie deficit produces slower, more sustainable loss of about 0.25 kg per week. Deficits beyond 1,000 kcal/day are generally not recommended without medical supervision as they risk lean mass loss and nutritional deficiencies.