Summary
Lean and fat mass split from weight and a supplied body-fat percentage.
Calculation details
Body-fat percentage must come from another estimate or measurement method.
Formula
Fat mass = weight × body-fat%; lean mass = weight − fat mass.
Worked example
Lean body mass worked example
70 kg at 20% body fat implies 14 kg fat mass and 56 kg lean mass.
How it works
Enter body weight and a body-fat percentage from another method. Poor body-fat inputs produce poor lean-mass estimates.
Frequently asked questions
Is this a medical diagnosis?
No. It is an educational estimate and cannot diagnose a condition or replace individualized professional advice.
Why can my actual result differ?
The split is only as good as the body-fat percentage you supply.
When is this calculator most useful?
Use it after you already have a body-fat estimate from another method.
How are results rounded?
The calculation retains full precision; centralized display formatting rounds only the visible result.