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Lean Body Mass Calculator (Boer Formula)

Estimate lean body mass and implied body fat from height and weight alone using the Boer formula, in metric or imperial units.

Lean body mass (Boer formula)
58.1 kg
Fat mass
17 kg
Implied body fat
22.6%

How it works

The Boer formula (1984) estimates lean body mass — everything that isn't fat: muscle, bone, organs, water — from just height and weight, without needing a tape measure or caliper. For men: LBM = 0.407×weight(kg) + 0.267×height(cm) − 19.2. For women: LBM = 0.252×weight(kg) + 0.473×height(cm) − 48.3.

Unlike the Devine ideal-weight or Navy body-fat formulas on this site, Boer's coefficients are calibrated directly for kilograms and centimeters rather than inches, so imperial entries are converted to metric before the formula runs and the results converted back — the answer is identical either way.

Fat mass is simply total weight minus lean body mass, and implied body fat percent is that fat mass as a share of total weight. This is a population-average regression, not a direct measurement, so it can produce an implausible result (lean mass at or above total weight) for unusual height/weight combinations — the calculator flags that instead of returning a negative fat mass.

FAQ

How is this different from the Navy body fat calculator on this site?

The Navy method estimates body fat percentage directly from neck, waist, and (for women) hip circumference measurements. The Boer formula instead estimates lean body mass from height and weight alone, with no tape measure needed — a different formula, a different set of inputs, and a different clinical use (Boer's result is commonly used for medication dosing and protein-intake targets).

What is lean body mass used for?

It's often used as a more relevant basis than total body weight for things like protein intake targets in strength training, or dosing certain medications where fat tissue doesn't affect the required amount the way lean tissue does.

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