Lean Body Mass Calculator

Estimate lean body mass with Boer (1984): a height-and-weight equation with separate male and female coefficients. The result is not fat-free mass from DEXA, and it will be rejected if it would exceed the scale weight you typed.

How to use

Choose units and which Boer equation to use, then enter current weight and height.
Read estimated LBM in kilograms (or the display unit). An 80 kg, 180 cm male-equation example is about 61.4 kg.
If the page rejects the inputs, the algebra was non-positive or larger than body weight — both are treated as invalid.
For a tape percent instead of an LBM kilogram, use Body Fat. Boer does not use neck or waist.

How it works

Lean body mass in this equation is “everything that is not estimated fat mass”: muscle, bone, organs, water, as Boer modelled them from height and weight. Male: 0.407×kg + 0.267×cm − 19.2. Female: 0.252×kg + 0.473×cm − 48.3. For 80 kg and 180 cm on the male line that is 0.407×80 + 0.267×180 − 19.2 = 32.56 + 48.06 − 19.2 ≈ 61.4 kg.

The result must be positive and strictly below scale weight. Fat-free mass cannot exceed the person. If the coefficients would overshoot — unusual proportions, a typo, or a very low weight with a large height — the calculator returns no figure instead of a physical impossibility.

Boer is an anthropometric estimate used in some clinical papers because it needs only a stadiometer and a scale. It will mis-read people the 1984 sample did not look like: very muscular athletes, sarcopenia, oedema, amputation. A tape (Navy) or imaging will disagree, sometimes by a lot. That disagreement is expected.

BMI and Devine ignore the current-weight term in different ways: BMI uses weight only as the numerator of kg/m²; Devine ignores weight entirely. Healthy Weight is a BMI range. None of those is LBM. Subtracting Boer LBM from scale weight is not a validated fat-mass measurement on this page — we do not print that remainder as “fat.”

Not medical advice. Dosing and nutrition decisions that mention LBM belong with a clinician using their chosen equation and a measured weight.

Formula

Male: 0.407×kg + 0.267×cm − 19.2
Female: 0.252×kg + 0.473×cm − 48.3

Worked examples

Boer male example
80 kg, 180 cm, male equation → about 61.4 kg

Useful notes

LBM must be positive and less than scale weight or the result is rejected.
Not DEXA, Bod Pod or a tape test.
Not medical advice.

FAQ

What is lean body mass?: Everything that is not fat mass — muscle, bone, organs, water — as estimated by this equation.
Why Boer?: It is a commonly cited height-and-weight LBM equation with separate male and female coefficients.
Can LBM exceed body weight?: Not in reality. If the equation would exceed scale weight, the result is rejected.
Is scale weight minus LBM my fat mass?: This page does not report that remainder. Boer is an estimate; treating the leftover as fat would overstate precision.
Does the tape test use Boer?: No. Body Fat uses Hodgdon & Beckett circumferences. Boer uses only height and weight.

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