Basal Metabolic Rate (BMR) Calculator
Calculate the calories your body burns at rest using the Mifflin-St Jeor equation.
Your basal metabolic rate (BMR) is the number of calories your body burns at complete rest just to keep you alive — powering your heart, brain, breathing and other basic functions over a full day. It is the largest single part of most people's daily energy use and the foundation for working out how much you should eat to lose, maintain or gain weight.
This calculator shows your BMR from two well-known equations. The Mifflin-St Jeor equation is the modern default and is generally considered the most accurate for the average person, while the revised Harris-Benedict equation is the classic formula included for comparison. Both use your sex, age, height and weight; they do not include activity, so multiply your BMR by an activity factor to estimate total daily calories.
How to use it
- 1Select your gender and choose Metric (cm, kg) or Imperial (ft, in, lb).
- 2Enter your age in years.
- 3Enter your height and weight in the chosen units.
- 4Read your BMR from the Mifflin-St Jeor equation, with the Harris-Benedict estimate for comparison.
Frequently asked questions
What is the Mifflin-St Jeor BMR formula?+
Using weight in kilograms, height in centimetres and age in years: BMR = 10 × weight + 6.25 × height − 5 × age, then add 5 for men or subtract 161 for women. It is widely regarded as the most accurate general-purpose BMR equation for healthy adults.
How is BMR different from TDEE?+
BMR is what you burn at complete rest. Total daily energy expenditure (TDEE) also includes movement, exercise and digesting food. You estimate TDEE by multiplying BMR by an activity factor — roughly 1.2 for sedentary up to about 1.9 for very active people.
Why do the two equations give different numbers?+
Mifflin-St Jeor and Harris-Benedict were derived from different study populations and use different coefficients, so their estimates usually differ by a modest amount. Neither is exact for any one person; treat them as close estimates and adjust based on how your weight actually changes.
Related calculators
Calculate your Body Mass Index in metric or imperial units and see your weight category.
Estimate your daily calorie needs (BMR and TDEE) for maintaining, losing or gaining weight.
Estimate your body fat percentage using the US Navy tape-measurement method.
Estimate your ideal body weight using the Devine, Robinson, Miller and Hamwi formulas.