Free Lean Body Mass Calculator
Use this free Lean Body Mass Calculator to find how much of your weight is lean tissue and how much is fat. Enter your sex, weight and height, and it applies the Boer formula in seconds.
You do not need a DEXA scan or a body-fat scale for a useful estimate. The result helps you track muscle gain, set protein targets and judge whether a change in weight is fat, muscle or both.
Table of Contents
What is a Lean Body Mass Calculator?
A Lean Body Mass Calculator estimates the weight of everything in your body except fat, including muscle, bone, water and organs. It gives a clearer picture than total weight alone, because two people at the same weight can have very different amounts of muscle and fat.
Formula (Boer): Men: LBM = 0.407 x weight + 0.267 x height – 19.2. Women: LBM = 0.252 x weight + 0.473 x height – 48.3. Fat mass = weight – LBM. Weight is in kilograms and height is in centimetres.
How to Use the Lean Body Mass Calculator (Step by Step)
- Select your sex.
- Enter your weight in kilograms and your height in centimetres.
- Press Calculate.
- See your lean mass and fat mass in the result.
Example Calculation
Example: Male, 80 kg, 180 cm. Lean Body Mass is 61.42 kg and Fat Mass is 18.58 kg. That means about 61.42 kg of the 80 kg total is lean tissue, and the remaining 18.58 kg is fat.
Features
- Boer formula, the height-weight formula closest to DEXA results.
- Lean mass and fat mass in one result.
- Separate formulas for men and women.
- Free and instant, with no sign-up needed.
Benefits
- Track muscle gain separately from fat gain.
- Set protein targets at about 2.2 g per kg of lean body mass.
- Set realistic body-composition goals instead of chasing scale weight alone.
Final Thoughts
Start with the defaults, check your lean and fat mass, and recheck over time to see whether training is adding muscle or only weight. For related tools, try the TDEE Calculator and the Macro Calculator.
Frequently Asked Questions (FAQs)
What is lean body mass?
Lean body mass is your total weight minus fat mass – it includes muscle, bones, organs and water. It is not the same as muscle mass alone.
Why is the Boer formula used?
Among height-weight formulas, Boer matches DEXA measurements most closely for normal and obese adults, better than the older James and Hume formulas.
How much lean mass should I have?
There is no single ideal number – it depends on height, sex and training. Athletes track LBM over time to confirm they are gaining muscle, not just weight.
Can LBM help set protein targets?
Yes. A common sports-nutrition rule is about 2.2 g protein per kg of lean body mass per day for muscle gain.