Lean Body Mass Calculator
Estimate your lean body mass and fat mass from height, weight, and gender.
feet
inches
centimeters
If known, this gives the most accurate result
Lean Body Mass
Fat Mass
Body Fat %
Method Comparison
| Method | Lean Body Mass | Fat Mass |
|---|
What Is Lean Body Mass?
Lean body mass (LBM) is the total weight of your body minus the weight of all your fat. It includes muscle, bone, organs, skin, connective tissue, and body water. Because it captures the metabolically active part of your body, LBM is a more meaningful figure than total weight for many health and fitness decisions. Two people of the same weight can have very different amounts of lean tissue, and tracking LBM over time tells you whether weight changes come from muscle or from fat.
Why Lean Body Mass Matters
- Katch-McArdle BMR: The Katch-McArdle equation estimates your basal metabolic rate directly from lean body mass (BMR = 370 + 21.6 × LBM in kg), which can be more accurate than weight-based formulas for lean or muscular individuals.
- Medication dosing: Many drugs, including anaesthetics and some chemotherapy agents, are dosed by lean body mass rather than total weight to avoid overdosing patients with higher body fat.
- Body-composition goals: Preserving or building lean mass during a diet is a key marker of healthy fat loss.
- Athletic performance: Strength and power often track with lean mass rather than total body weight.
Calculation Methods Explained
Boer Formula
The Boer formula estimates lean body mass from weight and height and is one of the most widely used equations in clinical practice. It is the default used for the headline result on this calculator.
Men: LBM = 0.407 × kg + 0.267 × cm − 19.2
Women: LBM = 0.252 × kg + 0.473 × cm − 48.3
Hume Formula
The Hume formula is an alternative weight-and-height equation, useful as a cross-check against the Boer estimate.
Men: LBM = 0.32810 × kg + 0.33929 × cm − 29.5336
Women: LBM = 0.29569 × kg + 0.41813 × cm − 43.2933
Body-Fat Percentage Method
If you have a measured body-fat percentage (from a DEXA scan, calipers, or a Bod Pod), lean body mass can be calculated directly. This is the most accurate approach because it uses your actual body composition rather than a population estimate. When a body-fat % is entered, this method becomes the headline result.
LBM = weight × (1 − body fat % / 100)
References
The formulas used in this calculator are based on peer-reviewed research:
- Boer, P. (1984). "Estimated lean body mass as an index for normalization of body fluid volumes in humans." American Journal of Physiology, 247(4), F632-F636. DOI: 10.1152/ajprenal.1984.247.4.F632
- Hume, R. (1966). "Prediction of lean body mass from height and weight." Journal of Clinical Pathology, 19(4), 389-391. DOI: 10.1136/jcp.19.4.389
- Katch, F.I. & McArdle, W.D. (1973). "Prediction of body density from simple anthropometric measurements in college-age men and women." Human Biology, 45(3), 445-455.
Note: This calculator provides estimates based on validated formulas but should not replace professional body composition analysis. The Boer and Hume formulas estimate lean body mass from height and weight and do not account for individual differences in muscularity or hydration. For the most accurate result, enter a measured body-fat percentage. Consult a healthcare professional for medical or dosing decisions.