Data Source and Methodology
- Boer P. "Estimated lean body mass as a function of height and weight." Journal of Parenteral and Enteral Nutrition. 1984;8(6): 608–611. DOI: 10.1177/0148607184008006608
- Hume R. "Prediction of lean body mass from height and weight." Journal of Clinical Pathology. 1966;19:389–391.
- James WPT, Waterlow JC. "Research on obesity: Clinical grading of obesity and lean body mass." British Journal of Nutrition. 1976;35(2): 139–148.
Direct links via PubMed and publisher sites where available. All equations are implemented using metric units and internally convert US/Imperial inputs to kilograms and centimeters.
Tutti i calcoli si basano rigorosamente sulle formule e sui dati forniti da questa fonte.
The Formula Explained
Boer (1984), male: \( \mathrm{LBM}_m = 0.407\,W + 0.267\,H - 19.2 \)
Boer (1984), female: \( \mathrm{LBM}_f = 0.252\,W + 0.473\,H - 48.3 \)
Hume (1966), male: \( \mathrm{LBM}_m = 0.32810\,W + 0.33929\,H - 29.5336 \)
Hume (1966), female: \( \mathrm{LBM}_f = 0.29569\,W + 0.41813\,H - 43.2933 \)
James (1976), male: \( \mathrm{LBM}_m = 1.10\,W - 128\,\frac{W^2}{H^2} \)
James (1976), female: \( \mathrm{LBM}_f = 1.07\,W - 148\,\frac{W^2}{H^2} \)
From body fat percentage: \( \mathrm{LBM} = W \times \left(1 - \frac{\mathrm{BFP}}{100}\right) \)
Where W = weight (kg), H = height (cm), BFP = body fat percent.
Glossary of Variables
- Weight (W): Your body weight. Input in kg (metric) or lb (US); converted to kg internally.
- Height (H): Your standing height. Input in cm (metric) or ft+in (US); converted to cm internally.
- Sex: Male or Female, required by the Boer, Hume, and James equations.
- Body Fat % (BFP): Optional measurement from calipers, BIA, DXA, or lab estimates. Required if using the "From Body Fat %" method.
- Lean Body Mass (LBM): Estimated fat-free mass in kg or lb.
- Fat Mass: Estimated fat mass = Weight − LBM (kg).
- Estimated Body Fat %: 100 × (Fat Mass ÷ Weight). When using BFP method, this equals the input BFP.
How It Works: A Step-by-Step Example
Scenario
Male, 180 cm, 80 kg. Using Boer (1984).
Steps
- Ensure units are metric. Select Male. Choose Boer (1984).
- Compute LBM: 0.407×80 + 0.267×180 − 19.2 = 32.56 + 48.06 − 19.2 = 61.42 kg.
- Convert to lb: 61.42 × 2.20462 ≈ 135.45 lb.
- Estimated body fat % from the equation’s LBM: 100 × (80 − 61.42)/80 ≈ 23.2% (an estimate; direct BFP input is preferred when available).
Frequently Asked Questions (FAQ)
Is LBM the same as fat-free mass?
Practically, yes—both exclude fat mass. Small definitional differences can exist in research contexts, but in most applications they are interchangeable.
Which equation should I choose?
Boer is often preferred in clinical and anesthesia contexts for general adults. Hume and James remain widely cited. If you have a reliable body fat %, the BFP method is most personalized.
Can I use this calculator for dosing medications?
No. While some clinical dosing uses lean body weight, you must follow your institution’s protocols and consult a qualified clinician.
How accurate are estimates for very short or very tall individuals?
Equations can lose accuracy at extremes of height/weight or with conditions affecting fluid balance. Consider device-based assessments (e.g., DXA) if precision is critical.
Does hydration affect results?
Equations themselves are unaffected by hydration, but your measured weight can vary with fluid status, indirectly affecting estimates.
Will you store my data?
No. All calculations are performed locally in your browser.
Medical disclaimer: This tool provides educational estimates only and is not a substitute for professional medical advice, diagnosis, or treatment.
Authorship and Review
Tool developed by Ugo Candido.
Content verified by CalcDomain Editorial Board.
Last reviewed for accuracy on: .