This lean body mass calculator estimates LBM from weight in kilograms, height in centimeters, and sex. The default male profile of 70 kg and 175 cm returns about 56.0 kg using 0.407×70 + 0.267×175 – 19.2.
Athletes and students use estimates like this for coursework and rough planning. It is not a DXA scan or medical diagnosis. Pair broader health math with tools such as BMI or calorie planners only when those pages match your question.
How the formula works
Male: 0.407w + 0.267h – 19.2. Female: 0.252w + 0.473h – 48.3. Weight w is in kg and height h is in cm. The result is an estimated lean mass in kilograms.
Worked example
Sex male, weight 70, height 175. 0.407×70 = 28.49. 0.267×175 = 46.725. Sum minus 19.2 ≈ 56.015 kg.
| Input | Value |
|---|---|
| Weight | 70 kg |
| Height | 175 cm |
| Sex | Male |
| Lean body mass | ~56.0 kg |
Lean Body Mass Formulas: Boer vs James vs Hume
All three are adult equations from height and weight (W = kg, H = cm). The calculator uses Boer. James and Hume are shown for comparison. For body surface area from the same two inputs, use the body surface area calculator.
| Formula | Men | Women |
|---|---|---|
| Boer (1984) | 0.407W + 0.267H − 19.2 | 0.252W + 0.473H − 48.3 |
| James (1976) | 1.1W − 128 × (W/H)² | 1.07W − 148 × (W/H)² |
| Hume (1966) | 0.32810W + 0.33929H − 29.5336 | 0.29569W + 0.41813H − 43.2933 |
Lean body mass examples (kg)
| Profile | Boer | James | Hume |
|---|---|---|---|
| Man, 70 kg, 175 cm | 56.0 | 56.5 | 52.8 |
| Man, 80 kg, 180 cm | 61.4 | 62.7 | 57.8 |
| Man, 90 kg, 178 cm | 65.0 | 66.3 | 60.4 |
| Woman, 55 kg, 160 cm | 41.2 | 41.4 | 39.9 |
| Woman, 60 kg, 165 cm | 44.9 | 44.6 | 43.4 |
| Woman, 70 kg, 165 cm | 47.4 | 48.3 | 46.4 |
The formulas can differ by several kilograms for the same person. The James equation becomes unreliable at high weight for a given height. In one study that checked Hume’s method against DXA scans, the typical error was about 3.6 kg. For a measured figure, a DXA scan or another clinical body-composition test is needed. To estimate fat mass, subtract your lean body mass from your weight, or try the body fat calculator. For resting energy, use the BMR calculator.
This is an educational estimate, not medical advice. Talk to a GP, doctor or registered dietitian before changing how you eat, especially if you are pregnant, under 18 or have a health condition.
How to use the fields
- Weight must be in kilograms.
- Height must be in centimeters.
- Sex chooses the male or female coefficient set.
What lean mass means here
Lean body mass roughly covers everything that is not fat mass in these educational formulas. Muscle, bone, and organs contribute. Individual athletes can differ a lot from population equations.
Common mistakes
- Entering pounds or inches without converting
- Treating the estimate as a lab measurement
- Using adult formulas for young children
- Confusing LBM with ideal body weight charts
Converting units first
Pounds to kilograms: divide pounds by 2.2046 roughly. Inches to cm: multiply by 2.54. Convert before you type values so the coefficients stay valid.
Fat mass sketch
If total weight is 70 kg and LBM is about 56 kg, the leftover near 14 kg is a rough fat mass sketch only. Hydration, glycogen, and formula error all move that leftover. Do not treat it as a clinical fat percentage without proper testing.
Training context
Coaches sometimes track estimated LBM across a season while weight changes. Keep the same formula and unit conventions every time so trends are comparable. Sudden swings deserve a measurement reality check, not just calculator trust.
Female default path
Switch sex to female with the same 70 kg and 175 cm to see how coefficients change the estimate. The female formula uses smaller weight weight and larger height weight plus a different constant. Comparing both on identical inputs shows why sex is a required field.
Always match the selection to the person you are modeling.
Classroom and homework use
Show the arithmetic lines for the default male case so students see each product. Then change height by 5 cm and predict the direction of change before recalculating. That habit builds formula sense beyond memorizing 56 kg.
Remind learners that online estimates do not replace clinician directed body composition testing.
Tracking over a season
If you log estimated LBM monthly, keep weight and height units fixed and keep the same sex selection. Mixed unit systems create fake trends that look like physiology but are only conversion errors.
Large week to week swings deserve a second weigh in under similar conditions before you rewrite a training plan.
Not a calorie prescription
LBM estimates sometimes feed other equations in textbooks. This page stops at LBM. Do not invent a calorie target from LBM alone without a method your coach or clinician endorses.
Hydration and glycogen change scale weight without changing true lean tissue much overnight.
Height measurement tips
Stand tall against a flat wall, barefoot, for height in centimeters. Small height errors move the estimate because height carries a sizable coefficient in both sex formulas.
Recheck height occasionally for teens who are still growing rather than reusing last year’s number forever.
Weigh in consistency
Use the same scale, similar clothing, and a similar time of day when you compare LBM estimates across weeks. Otherwise the formula faithfully reports noise from the weigh in rather than a true lean mass change.
Record weight, height, sex, and the resulting LBM together so later you can see which input moved.
Limitations
Population linear formulas miss many individual factors. Extremes of age, amputation, pregnancy, and certain medical conditions need clinical methods. Results are educational estimates only.
For related unit and percent checks while you plan materials, try the unit converter or the percentage calculator.