Katch-McArdle BMR Calculator
Estimate BMR from lean body mass.
Katch-McArdle uses lean mass, so it's accurate for lean/muscular people.
How the Math Works
The Katch-McArdle BMR Calculator uses a precise formula to estimate your basal metabolic rate based on lean body mass: BMR = 370 + 21.6 × lean mass. This equation multiplies your lean body mass (total body weight minus fat mass) by 21.6 and adds 370 calories. Unlike traditional formulas that rely on total body weight and gender, this method focuses specifically on metabolically active muscle tissue, making it particularly accurate for individuals with high muscle mass or unusual body compositions.
Practical Applications
To use this calculator, first determine your lean body mass through a DEXA scan, bioelectrical impedance analysis, or skinfold measurements. Once you have your lean mass in kilograms, simply multiply that number by 21.6, then add 370 to get your estimated BMR in calories. For example, someone with 50 kg of lean mass would calculate: 50 × 21.6 = 1,080, plus 370 equals 1,450 BMR calories per day. This measurement should be taken in the morning, fasting, for the most accurate reading.
Day-to-Day Use
Knowing your BMR through the Katch-McArdle method empowers you to make informed nutritional and fitness decisions. Your BMR represents the minimum calories your body needs at rest, helping you set realistic weight goals and adjust intake for weight loss or muscle gain. Fitness professionals often use this calculation to create personalized training programs, while individuals can track how changes in body composition—like gaining muscle or losing fat—affect their metabolic needs. This information is especially valuable for athletes, bodybuilders, and anyone seeking to optimize their health and performance through evidence-based nutrition planning.
Worked example
80 kg at 15% fat → LBM 68 kg → ~1,839 kcal.
FAQ
Need body fat?
Yes — that's what makes it precise for athletes.