About This Tool
The Body Recomp Engine is the only free tool that combines Navy body fat measurement with all three major BMR formulas in one place. The key advantage: Katch-McArdle is the most accurate BMR formula for active individuals, but it requires body fat percentage — which is exactly what the Navy method provides.
Why Katch-McArdle is more accurate
Most BMR calculators use weight as a proxy for lean mass. But two people with the same weight can have vastly different metabolic rates if one has 15% body fat and the other has 30%. Katch-McArdle calculates from lean mass directly, eliminating this error.
Navy Body Fat Method
The US Navy body fat formula uses circumference measurements to estimate body fat. It's validated against hydrostatic weighing and is accurate to within ±3% for most people. It requires waist, neck, and (for females) hip measurements.