BMR Calculator
Enter age, height, weight and activity level to see how many calories your body burns at rest and per day.
BMR is the energy your body burns at complete rest. TDEE multiplies it by your activity level. Eat about 500 kcal below TDEE to lose roughly 0.5 kg a week.
About this tool
Basal metabolic rate is the energy your body needs at complete rest to breathe, circulate blood and keep organs running: typically 60–70% of what you burn in a day. Mifflin-St Jeor (1990) is the most accurate general formula and the one dietitians use today; Harris-Benedict (1919, revised 1984) is shown for comparison.
Multiplying BMR by an activity factor gives total daily energy expenditure (TDEE), the number to eat to maintain weight. A deficit of about 500 kcal per day corresponds to roughly half a kilogram of fat per week; a surplus of 250–500 supports muscle gain. Use the Calorie Calculator for a target with a specific goal.
Frequently asked questions
- Which formula should I trust?
- Mifflin-St Jeor. Studies find it within 10% of measured values for most adults.
- Does muscle mass change BMR?
- Yes, muscle burns more at rest. These formulas use weight only; very muscular people may need slightly more.
- Should I eat below my BMR to lose weight?
- Not for long periods. Eat below TDEE but at or above BMR unless supervised by a professional.