BMR Calculator

BMR is the number of calories your body burns at complete rest to maintain vital functions like breathing, circulation, and cell production. It represents about 60-75% of your total daily calorie expenditure and is influenced by age, gender, weight, and body composition.

The Mifflin-St Jeor equation is considered most accurate for the general population according to research. The Katch-McArdle and Cunningham formulas are more accurate if you know your body fat percentage, as they account for lean body mass.

BMR (Basal Metabolic Rate) is measured under very strict conditions after 8+ hours of sleep and 12+ hours of fasting. RMR (Resting Metabolic Rate) is measured under less strict conditions and is typically 10-20% higher than BMR. Most calculators estimate RMR.

Muscle tissue is metabolically active and burns more calories at rest than fat tissue. One pound of muscle burns approximately 6-7 calories per day at rest, while fat burns only about 2 calories. This is why strength training can increase your BMR over time.

Yes, BMR typically decreases by 1-2% per decade after age 20, primarily due to loss of muscle mass (sarcopenia) and hormonal changes. Regular exercise and strength training can help slow this decline by maintaining muscle mass.

Eating below BMR for extended periods is not recommended as it can slow metabolism, cause muscle loss, and lead to nutritional deficiencies. Instead, create a moderate caloric deficit (300-500 below TDEE) while ensuring adequate protein and nutrients.