Lean Body Mass Calculator

Lean Body Mass (LBM) is your total body weight minus fat mass — everything else, including muscle, bone, organs and water. This calculator estimates it using the Boer formula, one of the more accurate equations available from simple height and weight inputs.

Fill in the form and select Calculate to see your result here.

What is Lean Body Mass?

LBM strips out fat mass to show what the rest of your body weighs. It is a useful reference point for setting protein intake and tracking body recomposition over time, since it changes far more slowly than scale weight.

Lean Body Mass Formula

The Boer formula estimates lean body mass from height, weight and gender without requiring skinfold or circumference measurements, and is regarded as one of the more accurate simple LBM equations for the general adult population.

Men: LBM = 0.407 × weight(kg) + 0.267 × height(cm) − 19.2
Women: LBM = 0.252 × weight(kg) + 0.473 × height(cm) − 48.3

Lean Body Mass Example

A 170 cm, 70 kg male: LBM = (0.407 × 70) + (0.267 × 170) − 19.2 = 28.5 + 45.4 − 19.2 ≈ 54.7 kg, meaning roughly 15.3 kg is fat mass (about 22% body fat).

How to Use This Calculator

Select your gender.
Enter your height and current weight.
Select "Calculate" to see your estimated lean body mass, fat mass and body fat percentage.
Use the Protein Calculator to set an intake target based on your lean mass rather than total weight.

Limitations

This is a population-based estimate, not a direct measurement — DEXA scans or BIA devices measure body composition directly and will be more accurate for any one individual.
The formula was validated on general adult populations and is less precise at the extremes (very lean athletes or people with obesity).
LBM includes bone, organs and water, not just muscle — it is not a direct "muscle mass" number.

Frequently Asked Questions

No — LBM includes muscle plus bone, organs, and body water. Muscle mass alone is a subset of LBM and requires more specialized measurement to isolate.

Protein needs scale more closely with lean mass than total body weight, especially for people carrying more body fat — using LBM can give a more individualized protein target.

Progressive resistance training combined with adequate protein intake and a slight calorie surplus (or maintenance, for recomposition) is the established approach — see the Workout and Protein Calculator sections.