How is lean body mass useful?

It gives a better basis than total weight for protein intake targets and some drug doses, and it helps interpret weight changes that are muscle rather than fat.

Is this as accurate as a DEXA scan?

No. Formula-based estimates are convenient but approximate. DEXA, calipers or the Navy body-fat method give more direct body-composition readings.

Is this as accurate as a DEXA scan?

No. Formula-based estimates are convenient but approximate. DEXA, calipers or the Navy body-fat method give more direct body-composition readings, especially at extreme body sizes.

Health & Fitness Calculators

Lean Body Mass Calculator

Lean body mass is your total weight minus body fat — muscle, bone, organs and water. It is a useful reference for setting protein targets and for some medical drug dosing, and it gives context that body weight alone cannot.

Enter your sex, height and weight. The calculator uses the Boer formula to estimate lean body mass and the implied fat mass.

It is useful for setting protein targets, interpreting weight changes, and understanding some medical dosing — anywhere that muscle-and-organ mass matters more than total weight.

Sex

Heightcm

Weightkg

Enter your values to see the result.

How this is calculated

Lean body mass is your total weight minus body fat — muscle, bone, organs and water. This calculator estimates it from sex, height and weight using the Boer formula: 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. The implied fat mass is your weight minus the lean body mass.

LBM is a useful reference because some targets and doses scale better with lean mass than with total weight. Protein intake, for example, is often set per kilogram of body weight but is really feeding lean tissue.

The Boer formula is well-validated but still an estimate; it cannot match the accuracy of DEXA, calipers, or the Navy body-fat method, all of which measure composition more directly. The model does not account for hydration status (water is part of lean mass and shifts daily), age-related muscle loss, or extreme body sizes where estimation formulas break down. Treat the result as a reasonable approximation, not a precise measurement.

Worked example

A man, 175 cm tall, weighing 70 kg.

10.407 × weight = 0.407 × 70 = 28.49.
20.267 × height = 0.267 × 175 = 46.73.
3LBM = 28.49 + 46.73 − 19.2 = 56.0 kg; implied fat mass = 70 − 56.0 = 14.0 kg.

Frequently asked questions

What is the Boer formula?: 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. It is a well-validated estimation formula.
How is lean body mass useful?: It gives a better basis than total weight for protein intake targets and some drug doses, and it helps interpret weight changes that are muscle rather than fat.
Is this as accurate as a DEXA scan?: No. Formula-based estimates are convenient but approximate. DEXA, calipers or the Navy body-fat method give more direct body-composition readings.
What is the Boer formula?: 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. It is a well-validated estimation formula.
Is this as accurate as a DEXA scan?: No. Formula-based estimates are convenient but approximate. DEXA, calipers or the Navy body-fat method give more direct body-composition readings, especially at extreme body sizes.

Related calculators

Method: Boer lean-body-mass estimation formula. No external data source. Last updated: September 2026.

These results are general estimates from established formulas and are not medical advice. They depend on the accuracy of the values you enter and on individual factors the formulas cannot capture. Consult a qualified healthcare professional before making decisions about your diet, training or treatment.