Lean mass guide
Lean Mass Percentage Calculator
Calculate lean mass percentage from body fat percentage and learn how to interpret lean mass percent by context.
Last updated: · Reviewed by the Lean Mass Calculator editorial team
Who this page is for
People who want lean mass as a percentage of body weight instead of only kg or lb.
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.
Simple calculation
Lean mass percentage is 100 minus body fat percentage. If you are 22% body fat, your lean mass percentage is 78%.
The homepage calculator shows lean mass percentage alongside fat mass and total lean mass.
How to interpret it
A higher lean mass percentage usually means lower body fat, more lean tissue, or both. It does not tell you exactly how much skeletal muscle you have.
Compare lean mass percentage with total weight. A lighter person and heavier person can have the same percentage but very different lean mass in kg.
Frequently asked questions
What is a good lean mass percentage?
Many healthy adults fall roughly between 70% and 90%, but sex, age, and athletic goals change the interpretation.
Is lean mass percentage better than BMI?
It is more body-composition specific than BMI, but it depends on the accuracy of your body-fat 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)