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Ubify Financial Advisory Board
FINANCIAL ANALYSTS & CPA REVIEWERS
About This Tool
The Lean Body Mass Calculator estimates your non-fat body massโincluding skeletal muscle, bone mineral content, vital organs, and body waterโusing validated anthropometric equations.
### Boer and James Anthropometric Formulas Clinical research uses height and total weight to predict fat-free mass without requiring hydrostatic weighing tanks or DEXA scans: - **Boer Formula (Men)**: $$\text{LBM} = (0.407 \times \text{Weight}_{\text{kg}}) + (0.267 \times \text{Height}_{\text{cm}}) - 19.2$$ - **Boer Formula (Women)**: $$\text{LBM} = (0.252 \times \text{Weight}_{\text{kg}}) + (0.473 \times \text{Height}_{\text{cm}}) - 48.3$$ - **James Formula (Men)**: $$\text{LBM} = (1.1 \times \text{Weight}_{\text{kg}}) - 128 \times \left(\frac{\text{Weight}_{\text{kg}}}{\text{Height}_{\text{cm}}}\right)^2$$ - **James Formula (Women)**: $$\text{LBM} = (1.07 \times \text{Weight}_{\text{kg}}) - 148 \times \left(\frac{\text{Weight}_{\text{kg}}}{\text{Height}_{\text{cm}}}\right)^2$$ - **Adipose Fat Mass**: $\text{Fat Mass} = \text{Weight} - \text{LBM}$, with body fat percentage evaluated as $(\text{Fat Mass} / \text{Weight}) \times 100$.
### Worked Calculation Example Consider an **$80.0\text{ kg}$** male standing **$180\text{ cm}$** tall: - **Boer LBM**: $$\text{LBM} = (0.407 \times 80) + (0.267 \times 180) - 19.2 = 32.56 + 48.06 - 19.2 = 61.42\text{ kg} \approx 61.4\text{ kg}$$ In imperial units: $61.42 \times 2.20462 \approx 135.4\text{ lbs}$ of lean tissue. - **Derived Fat Mass**: $80.0 - 61.42 = 18.58\text{ kg}$ ($18.6\text{ kg}$) - **Estimated Body Fat**: $(18.58 / 80.0) \times 100 = 23.2\%$ - **James LBM**: $(1.1 \times 80) - 128 \times (80 / 180)^2 = 88 - 25.28 = 62.7\text{ kg}$.
### Private Client-Side Health Calculation All health calculations evaluate locally inside your web browser. No body weight, personal height, or biometric data are transmitted over the web.
How to Use
- 1
Select your biological gender (Male or Female) to apply sex-specific coefficients.
- 2
Enter your total body scale weight in kilograms (kg).
- 3
Input your standing height in centimeters (cm).
- 4
Read your estimated Lean Body Mass (Boer & James models), derived body fat percentage, and fat mass.
Frequently Asked Questions
Why is Lean Body Mass more useful than total weight for fitness goals?
Lean Body Mass reflects metabolically active tissue (muscle, bone, and organs). Tracking LBM ensures weight loss comes from body fat rather than lean muscle tissue.
How do Boer and James equations differ?
The Boer equation uses a linear dual-variable model that works consistently across normal and overweight adults, while the James equation uses a squared weight-to-height ratio.
Are my health numbers uploaded to a remote server?
No. All anthropometric formulas execute 100% locally in your browser.