Formula | LBM (kg) | LBM (lb) | Body Fat (%) |
---|---|---|---|
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Lean body mass (LBM) is the portion of your weight that is not fat: muscle, bone, organs, water and other fat-free tissues. Because LBM drives basal energy needs and athletic potential, knowing it contextualises weight changes better than body mass index or scale readings alone. Clinicians also reference LBM when calculating drug dosages and monitoring recovery.
Enter your weight, height and sex, then select a recognised clinical formula. A reactive engine instantly applies the equation, converts units automatically and presents lean body mass, fat mass and body-fat percentage. A charting layer and comparison table let you inspect four formulas side-by-side, spotlighting how methodology affects numerical results.
Use the estimate to fine-tune calorie targets, adjust resistance-training volume or decide whether a gaining or cutting phase makes sense today. Athletes may track weekly trends, while clinicians may cross-check bedside measures during recovery. This calculator offers informational estimates, not medical advice; consult a qualified professional before making health or dosing decisions.
Lean body mass calculations rely on anthropometric regression models that link observable measurements (weight and stature) to laboratory-measured fat-free mass obtained via hydrostatic weighing or dual-energy X-ray absorptiometry. The Boer, James, Hume and Janmahasatian equations adjust for sex, height and nonlinear weight relationships to approximate composition without imaging equipment. Estimating LBM supports drug dosing, sports nutrition and longitudinal monitoring across diverse age groups and clinical settings where direct measurement tools are unavailable.
Boer
(replace with 0.252 · W + 0.473 · H − 48.3 for female)
James
(use 1.07 and 148 for female)
Hume
(replace with 0.29569 · W + 0.41813 · H − 43.2933 for female)
Janmahasatian
Body-Fat Category | Men (%) | Women (%) |
---|---|---|
Essential fat | 2–5 | 10–13 |
Athletes | 6–13 | 14–20 |
Fitness | 14–17 | 21–24 |
Acceptable | 18–24 | 25–31 |
Obese | >25 | >32 |
Compare your calculated fat percentage to the ranges above to contextualise health status and performance potential; aim for gradual, sustainable changes.
Parameter | Meaning | Unit | Typical Range |
---|---|---|---|
W | Body weight | kg | 30–200 |
H | Standing height | cm | 120–220 |
Sex | Coefficient selector | — | male / female |
Formula | Regression model | — | Boer · James · Hume · Janmahasatian |
Boer (male) with 70 kg and 175 cm:
LBM ≈ 56.0 kg; body-fat ≈ 20 %.
Formulas originate from peer-reviewed studies: Boer 1984, James 1976, Hume 1966, and Janmahasatian 2005. Comparative analyses report mean absolute errors under 3 kg against DXA benchmarks.
No personal data leaves your device, supporting GDPR-aligned data minimisation.
Follow these steps to obtain a quick composition snapshot.
Everything runs locally; no values are transmitted or saved.
Accuracy varies by population. Boer offers balanced performance, but comparing all four captures uncertainty.
Smart scales use bio-impedance, which fluctuates with hydration. Regression equations rely only on weight and height.
The models target adults; paediatric-specific equations are required for reliable child assessment.
Weekly measurements under similar conditions reveal meaningful trends without day-to-day noise.