Lean Body Mass Calculator

1. Enter your sex, height, and weight. The calculator uses three validated anthropometric formulas (Boer, James, Hume) that estimate LBM from these measurements. All three give slightly different results, and the average provides the best estimate.
2. Enter body fat % (optional). If you know your body fat percentage from a DEXA scan, Navy method, or caliper test, the calculator shows LBM directly: LBM = total weight × (1 - BF%). This method is more accurate than the formulas when you have a reliable BF% measurement.
3. Use LBM for calorie needs. The Katch-McArdle BMR formula uses LBM instead of total weight, giving a more accurate metabolic rate for both lean and muscular individuals.

Boer (men):    LBM = 0.407W + 0.267H - 19.2
Boer (women):  LBM = 0.252W + 0.473H - 48.3

James (men):   LBM = 1.1W - 128(W/H)²
James (women): LBM = 1.07W - 148(W/H)²

Hume (men):    LBM = 0.3281W + 0.3393H - 29.5336
Hume (women):  LBM = 0.2969W + 0.4169H - 43.2933

W = weight in kg, H = height in cm
From BF%: LBM = W × (1 - BF%/100)

Katch-McArdle BMR (uses LBM instead of weight):

BMR = 370 + (21.6 × LBM in kg)

Example: LBM = 65 kg
BMR = 370 + (21.6 × 65) = 370 + 1,404 = 1,774 cal/day