Katch-McArdle Calculator
Most BMR equations only know your weight, so they can't tell muscle from fat. Katch-McArdle works from your lean body mass instead — which means it needs your body fat percentage. If you don't know it, our Body Fat Calculator will estimate it from a few tape measurements.
Lean body mass
kg
Weight × (1 − body fat %)
Katch-McArdle
kcal/day
370 + 21.6 × lean mass (Cunningham 1991)
Cunningham 1980
kcal/day
500 + 22 × lean mass
Two lean-mass equations, shown separately. Both are only as accurate as the body fat figure you enter.
Your results are attached to the form below
These figures are estimates for general awareness only and are not medical advice or a diagnosis. Read our Medical Disclaimer.
Want a Plan Built Around Your Numbers?
A certified dietitian will turn these figures into a diet that fits your routine and your food.
How this is calculated
Lean body mass = weight × (1 − body fat %). Katch-McArdle: BMR = 370 + 21.6 × lean body mass (kg), the general prediction equation published by Cunningham in the American Journal of Clinical Nutrition (1991). Shown separately: Cunningham's earlier equation (1980), BMR = 500 + 22 × lean body mass.
Who it's for
Lean mass is the main driver of resting metabolism: Cunningham's 1991 review found it alone explains 65–90% of the differences between people. That makes a lean-mass equation a good fit for people whose body composition is far from average, such as the very muscular.
Only as good as your body fat number
A body fat estimate that's 5 points out changes your lean mass, and so your BMR, noticeably. Use the same method each time you measure — the tape-measure US Navy method in our Body Fat Calculator is a practical option at home.
Don't know your body fat?
Use the Mifflin-St Jeor BMR Calculator, which needs only height, weight, age and sex. The TDEE Calculator shows Katch-McArdle alongside the other equations when you add a body fat figure.
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- Maintenance Calorie Calculator The calories that keep your weight steady — today, and at your goal weight, so you know what to eat once you get there.