BMR Calculator
Calculate your Basal Metabolic Rate — the calories your body burns at complete rest — using both the Mifflin-St Jeor and Harris-Benedict equations.
About this calculator
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest just to maintain basic functions — breathing, circulation, and cell repair. This calculator computes BMR using two equations: Mifflin-St Jeor (1990), considered the most accurate for the general population, and Harris-Benedict (revised 1984). The result card also shows a full TDEE (Total Daily Energy Expenditure) table using the Mifflin result scaled by standard activity multipliers, so you can see your true calorie needs at any activity level.
Field explanations
- Sex
- Both formulas use different constants for males and females to account for average differences in lean body mass.
- Units
- Imperial uses feet, inches, and pounds; metric uses centimeters and kilograms. All inputs are converted to metric internally.
- Age
- BMR decreases with age as muscle mass typically declines. Both formulas include age as a direct input.
- Height
- Taller individuals have more surface area and organ mass, raising BMR. Enter feet and inches separately in imperial mode.
- Weight
- Heavier individuals burn more calories at rest. Note that muscle burns more than fat — two people at the same weight may have meaningfully different BMRs.