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Lean Body Mass Calculator
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Lean Body Mass Calculator

Calculate your lean body mass excluding fat weight.

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Lean Body Mass Calculator runs entirely on your device using Web API standards. No data is ever uploaded to UtilixVerse servers.

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Lean Body Mass Calculator

Calculate lean body mass (LBM) excluding body fat using Boer, James, and Hume medical formulas.

Estimated Lean Body Mass (Boer Formula)
56.0kg
Lean Mass: 80.0%•Fat Mass: 20.0%
Lean Mass Weight56.0 kg / 123.5 lbs
Body Fat Mass14.0 kg / 30.8 lbs

Formula Comparison Summary

Boer Formula (Standard)56.0 kg (123.5 lbs)
James Formula56.5 kg (124.6 lbs)
Hume Formula52.8 kg (116.4 lbs)

Understanding Lean Body Mass (LBM)

Your Lean Body Mass (LBM) represents the portion of your body composition that consists of non-fat components — including muscle mass, bone density, internal organs, fluids, and connective tissue. Subtracting body fat mass from total body weight gives your exact lean mass.

Medical Formulas Used for LBM Estimation

  • • Boer Formula:Widely recommended by clinical research for standard and overweight body types.
  • • James Formula:Classic formula based on height-to-weight ratio. Accurate for average body compositions.
  • • Hume Formula:Calibrated using statistical regression for broad populations.

Medical Disclaimer: This calculator provides clinical estimates based on statistical formulas. It does not replace direct DEXA scans, hydrostatic weighing, or professional medical evaluation.

Frequently Asked Questions About Lean Body Mass

What is Lean Body Mass (LBM)?

Lean Body Mass (LBM) is the total weight of your body minus all fat weight. It includes organs, bones, muscles, tendons, water, and essential structural tissue.

How is Lean Body Mass calculated?

Lean Body Mass can be estimated using validated medical formulas based on weight, height, and gender — including the Boer, James, and Hume formulas. If your body fat percentage is known, LBM can also be calculated directly as Total Weight × (1 - Body Fat %).

Why is tracking Lean Body Mass important for fitness?

Tracking Lean Body Mass helps ensure that weight loss comes from body fat rather than muscle loss during caloric deficits. It is also crucial for calculating Basal Metabolic Rate (BMR) and daily protein requirements.

What is the difference between Boer, James, and Hume formulas?

The Boer formula is considered the gold standard for normal and moderately overweight adults. The James formula is historically widely used, while the Hume formula provides accurate estimates across diverse body types. Our calculator displays results from all three formulas for comparison.

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