Lean Body Mass Calculator for Men
Estimate your lean body mass with the male formula coefficients pre-selected. Enter your height and weight, or a measured body fat % for an exact figure.
Lean Body Mass Calculator for Men
Required: the lean-mass formulas use biological sex (male or female) as a variable.
Range: 30–300 kg
Enter your height in centimeters (e.g., 170 cm)
Used only to flag whether the result needs an under-19 caveat — it does not change the formula. Leave blank if you'd rather not say.
Know your body fat %? Enter it for the most accurate result (lean mass = weight × (1 − body fat%)). Leave it blank to use the height & weight formulas. Don't know it? Estimate it with the Body Fat % Calculator.
The average of the Boer, James and Hume estimates — the most balanced default. A measured body fat % above always overrides the formula estimate.
*This calculator is for informational purposes only. Please consult a healthcare professional before making any health decisions. See our medical disclaimer for more information.
Quick Answer
Lean Body Mass for Men
This page loads the lean body mass calculator with male pre-selected, so the formulas use the coefficients derived for men. Lean body mass is everything that is not fat — muscle, bone, organs and water — and for men it is commonly a higher share of body weight than for women, reflecting lower essential fat. Enter your height and weight above for an estimate, or add a measured body fat % for an exact figure.
Why Sex Is a Variable in the Formula
The lean-mass formulas ask for biological sex for one plain reason: on average, men and women of the same height and weight divide that weight between fat and lean tissue differently. Men typically carry a smaller proportion of essential fat and a somewhat larger share of lean tissue. The Boer, James and Hume equations encode that average by using a different constant or multiplier for male bodies, so the same height and weight yield a different lean-mass estimate depending on the sex entered. It is worth being clear about what this is: a statistical adjustment for a population average, not a statement that one body is superior. Real men vary widely around that average, which is precisely why a measured body fat percentage always outperforms the sex-based estimate.
A Worked Example for a Man
Take a man who is 178 cm and 80 kg. Run his numbers through the three formulas and they land a few kilograms apart: the Boer estimate is about 60.9 kg of lean mass, James about 62.1 kg, and Hume about 57.1 kg. Their average is roughly 60.0 kg, which works out to a lean-mass share of about 75% of his body weight and, by definition, a body fat of around 25%. Those are the figures the tool above returns for those inputs. The five-kilogram gap between the highest and lowest formula is normal and comes from their different derivation populations — which is exactly why the calculator shows all three, plus their average, rather than pretending a single number is the answer.
Making the Number More Accurate
The single best upgrade to a formula estimate is a measured body fat percentage. Get one from the Body Fat % Calculator and enter it above, and the tool reports your lean mass exactly as weight minus fat mass rather than estimating it. Lean mass is also the most accurate basis for your metabolism: the Katch-McArdle Calculator works out your resting and daily calorie burn from lean body mass instead of total weight, which suits leaner, more muscular builds. To keep that lean tissue while dieting, a daily protein target from the Protein Intake Calculator is the main lever. The general version with the formula selector is the Lean Body Mass Calculator.
Lean mass is estimated with the Boer (1984), James (1976) and Hume (1966) formulas using the male coefficients, or computed directly from a measured body fat %. Typical ranges are descriptive of what is commonly observed, not targets. These figures are general estimates for education, not medical advice.
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