Lean mass guide
Lean Mass Calculator With Body Fat Percentage
Use measured body fat percentage to calculate lean mass directly instead of relying on height-weight formulas.
Last updated: · Reviewed by the Lean Mass Calculator editorial team
Who this page is for
People with DEXA, caliper, BIA, or Navy tape body-fat estimates.
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.
Why direct body-fat input is preferred
Height-weight equations estimate lean mass indirectly. A measured body fat percentage lets the calculator subtract fat mass directly from body weight.
The result is still only as accurate as the body-fat method. DEXA usually beats consumer BIA scales, but consistency matters for tracking.
Direct calculation example
If you weigh 80 kg at 20% body fat, fat mass is 16 kg and lean mass is 64 kg.
That direct lean mass value can then feed protein targets, FFMI, and Katch-McArdle BMR estimates.
Frequently asked questions
Does body fat percentage override the formula?
Yes. On the homepage calculator, entering body fat percentage takes priority over Boer, James, or Hume.
Which body-fat method should I use?
Use DEXA when available, or use the same caliper, BIA, or tape method consistently over time.
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)