Lean Body Mass Calculator Lean Body Mass Calculator Calculate your lean body mass (LBM) — the weight of your body minus the fat Metric (kg/cm) Imperial (lb/in) Age Gender Male Female Height (cm) Weight (kg) Body Fat Percentage ⓘIf you know your body fat percentage, enter it here. Otherwise, leave blank and we'll estimate it. Activity Level ⓘUsed for ideal weight calculations Sedentary (little or no exercise) Lightly Active (light exercise 1-3 days/week) Moderately Active (moderate exercise 3-5 days/week) Very Active (hard exercise 6-7 days/week) Extremely Active (very hard exercise, physical job) Boer Formula James Formula Hume Formula Calculate LBM Reset Download PDF Your Lean Body Mass Results Lean Body Mass 0 kg Weight of everything except fat Body Fat Mass 0 kg Total weight of body fat Body Fat Percentage 0% Status will appear here Body Composition Visualization 80% 20% Lean Body Mass Body Fat Ideal Weight Range 0 - 0 kg Based on your lean body mass and healthy body fat percentage range What is Lean Body Mass? Lean Body Mass (LBM) is the weight of everything in your body except fat. This includes your muscles, bones, organs, water, and other non-fat tissues. LBM is an important metric for tracking fitness progress, calculating caloric needs, and determining ideal weight ranges. Unlike weight alone, LBM gives you insight into your body composition. Two people with the same weight can have very different body compositions and health profiles based on their lean body mass and body fat percentages. Calculation Formulas This calculator offers three different formulas to estimate your lean body mass. Each formula may give slightly different results: Boer Formula (1984) Men: LBM = 0.407 × Weight(kg) + 0.267 × Height(cm) - 19.2 Women: LBM = 0.252 × Weight(kg) + 0.473 × Height(cm) - 48.3 The Boer formula is widely used for pharmaceutical dosing calculations and generally provides good estimates for most adults. James Formula (1976) Men: LBM = 1.1 × Weight(kg) - 128 × (Weight(kg)/Height(cm))² Women: LBM = 1.07 × Weight(kg) - 148 × (Weight(kg)/Height(cm))² The James formula is considered reasonably accurate for normal-weight individuals but may overestimate LBM in obese individuals. Hume Formula (1966) Men: LBM = 0.32810 × Weight(kg) + 0.33929 × Height(cm) - 29.5336 Women: LBM = 0.29569 × Weight(kg) + 0.41813 × Height(cm) - 43.2933 The Hume formula is one of the earliest equations for estimating lean body mass and is still commonly used in medical research. Note: While these formulas provide useful estimates, the most accurate measurements of lean body mass come from methods like DEXA scans, hydrostatic weighing, or BIA (Bioelectrical Impedance Analysis).
