BMR calculator
Calculate your basal metabolic rate with three equations side by side: Mifflin-St Jeor, the revised Harris-Benedict and, if you know your body fat, Katch-McArdle. Metric or US units.
Three equations, one answer to trust
Every BMR calculator is an equation fitted to people whose metabolism was measured in a lab. They disagree a little, which is useful information in itself: if the three results below are close, you can be fairly confident; if they diverge, your body composition is probably unusual and Katch-McArdle (with a good body-fat estimate) deserves more weight.
Harris-Benedict men: 88.362 + 13.397W + 4.799H − 5.677A
(revised 1984) women: 447.593 + 9.247W + 3.098H − 4.330A
Katch-McArdle 370 + 21.6 × lean mass(kg)
W = weight in kg · H = height in cm · A = age in years
Why your BMR matters
BMR is the floor of your energy budget. Multiply it by an activity factor and you get your TDEE, the number that decides whether you gain, lose or maintain weight. BMR falls slowly with age and rises with muscle mass, which is one reason strength training helps long-term weight management.
Not sure of your body-fat percentage? The body fat calculator estimates it with a tape measure.
Questions
What is BMR?
Basal metabolic rate is the energy your body needs at complete rest to keep you alive: breathing, circulation, temperature and cell repair. It is usually the largest part of daily energy use, often around 60–70% for sedentary adults.
Which BMR formula is most accurate?
For most healthy adults, Mifflin-St Jeor. If you know your body-fat percentage reliably, Katch-McArdle can be better for lean, muscular people because it works from lean mass.
Is BMR the same as RMR?
Nearly. Resting metabolic rate is measured under slightly less strict conditions and is a little higher, but the two terms are often used interchangeably in calculators.
Can I eat below my BMR?
Very low intakes are hard to sustain and can make it difficult to meet nutrient needs. Most people losing weight should eat between their BMR and their TDEE unless supervised by a clinician.
Sources
- Mifflin MD, St Jeor ST, et al. Am J Clin Nutr. 1990;51(2):241–247.
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated. Am J Clin Nutr. 1984;40(1):168–182.
- McArdle WD, Katch FI, Katch VL. Exercise Physiology: Nutrition, Energy, and Human Performance (Katch-McArdle equation).
- Frankenfield D, et al. J Am Diet Assoc. 2005;105(5):775–789.
Built and checked by Ingrid Solberg. Last reviewed October 22, 2026. All formulas: formulas & sources.