Lean mass guide
Lean Mass Calculator for Men
Estimate male lean body mass, fat mass, lean mass percentage, and protein targets with sex-specific formulas.
Last updated: · Reviewed by the Lean Mass Calculator editorial team
Who this page is for
Men comparing formula estimates with measured body fat percentage.
Start with the main lean mass calculator, then use the related tools below when you need body fat, FFMI, protein, or calorie context.
Interactive Calculator
Use this calculator to find your specific numbers before continuing with the guide.
Best formula choice for men
For men without a measured body fat percentage, the Boer equation is the best default on this site because it behaves well across common adult height and weight ranges.
If you know your body fat percentage from DEXA, calipers, or a consistent BIA device, use the direct body-fat method instead of any height-weight formula.
How to interpret the result
Lean mass includes muscle, bone, organs, connective tissue, and water. It is not the same as skeletal muscle mass.
For dieting, track whether lean mass is stable while body weight falls. If lean mass drops quickly, calories, protein, training, or measurement consistency may need attention.
Typical lean mass numbers for men
As a rough reference, an average adult man carries roughly 75-85% of his body weight as lean mass, so a 180 lb (81.6 kg) man is often in the region of 135-153 lb of lean mass depending on body fat. Trained lifters sit at the higher end; higher body-fat individuals sit lower.
If you want to know how much of that lean mass is actual muscle rather than bone, organs, and water, run the same stats through the muscle mass calculator, which estimates skeletal muscle mass specifically using the Lee (2000) equation.
Frequently asked questions
What is a good lean mass percentage for men?
Many healthy adult men fall around 75-90% lean mass, but age, training status, and body fat goals change the context.
Should men use FFMI too?
FFMI is useful when you want to compare fat-free mass relative to height, especially for strength or physique goals.
How much of my lean mass is muscle?
Skeletal muscle is only part of lean body mass, which also includes bone, organs, and water. In healthy men, skeletal muscle is roughly 40-45% of total body weight, so it is always a smaller number than lean mass. Use the muscle mass calculator for a skeletal-muscle-specific estimate.
Sources & references
The estimates on this page use published lean body mass equations and clinical reference ranges. See the full reference charts on the lean body mass chart hub.
- Estimated lean body mass as an index for normalization of body fluid volumes — Boer P, American Journal of Physiology (PubMed) (1984)
- Percent Body Fat Norms and Reference Ranges — American Council on Exercise (ACE)
- Body Composition — Reference Information — National Institutes of Health (NCBI Bookshelf)