Free body composition tool
Lean Body Mass Calculator
Lean body mass is everything in your body that is not fat: muscle, bone, organs and water. Enter your weight and height for two published estimates, or add a body fat percentage for a third.
Worked example
For a 30-year-old man who weighs 75 kg and is 178 cm tall, the Boer (1984) formula gives a lean body mass of 58.9 kg (129.7 lb) and the Hume (1966) formula 55.5 kg (122.3 lb). With a body fat of 18%, weight times the lean share gives 61.5 kg.
Estimate your lean body mass
The result below starts from the example's numbers. Change any field and it updates as you type.
Track this target every day
Use the number above as your daily goal in CalorTracker, then log meals by photo, voice or text and see where your day stands against it. Free to start, no card needed to explore.
Results are estimates from published formulas, not medical advice. Your own body can sit above or below them.
Where the formulas come from, and how we check them: how we calculate.
Three ways to estimate it
The calculator gives three figures, and shows them side by side because they are estimates that will not agree exactly. The first two need only weight and height. The third needs a body fat percentage, which you can get from the body fat calculator or from a scan.
The Boer formula
Boer (1984) published estimated lean body mass as an index for normalizing body fluid volumes. In kilograms, with weight in kg and height in cm, for men it is 0.407 × weight + 0.267 × height − 19.2. For women it is 0.252 × weight + 0.473 × height − 48.3.
The Hume formula
Hume (1966) found that lean body mass could be predicted from height and weight. For men: 0.3281 × weight + 0.33929 × height − 29.5336. For women: 0.29569 × weight + 0.41813 × height − 43.2933. Same units.
From a body fat percentage
If you know your body fat percentage, lean mass is simply weight × (1 − body fat ÷ 100). That figure is only as good as the body fat percentage it starts from, and different ways of measuring body fat disagree with each other. Leave the field blank to see the two formulas alone.
What it is for
People use lean mass to compare two measurements of the same person over time, or as an input to other formulas. It is not a score. The formulas estimate a population average from weight and height, so they cannot see how much of your weight is muscle. Two people with the same weight and height get the same answer from them. If you are pregnant, have a medical condition, or are worried about your weight or your body, talk to your doctor. This page makes no health claims about any result.
Sources
Boer P, Am J Physiol 1984;247:F632-F636. Hume R, J Clin Pathol 1966;19:389-391. All our sources are on the sources page.