Calculate your lean body mass (LBM) — the weight of everything in your body except fat, including muscle, bone, water, and organs. Lean mass is the key metric for nutrition and training programs.
Enter Your Measurements
Results
Lean Body Mass
144.0
lbs
Fat Mass
36.0
lbs
Lean Body Mass
65.3
kg
Formula
How to Use This Calculator
How to Use
- 1
Enter your total body weight.
- 2
Enter your body fat percentage (use the Navy Method calculator if unknown).
- 3
Your lean body mass and fat mass are calculated instantly.
Frequently Asked Questions
Frequently Asked Questions
Why is lean body mass important?
In-Depth Guides
Body Fat Percentage: How to Measure and What's Healthy
Understand body fat percentage ranges for men and women, how to measure accurately, and practical goals.
Lean Body Mass: What It Is and Why It Matters More Than Scale Weight
Understand lean body mass, how to calculate it, and why tracking it reveals true body composition progress.
How to Calculate Body Fat Percentage: Methods and Accuracy
Compare body fat measurement methods — Navy method, calipers, DEXA, bioelectrical impedance — with accuracy ratings and how to use each.
Related Calculators
Related Calculators
About This Calculator
This calculator uses the formula: LBM = Total Weight × (1 − Body Fat %); Fat Mass = Total Weight × Body Fat %. All calculations follow industry-standard methods. Results are estimates — always verify with a licensed professional for structural or code-compliant work.
Built and maintained by the CalcSmart team. Last updated March 2026.
▶Embed this calculator on your website
Copy and paste this code into your page:
<iframe src="https://calcsmart.io/embed/fat-free-mass-calculator" width="100%" height="520" frameborder="0" style="border-radius:8px;border:1px solid #e5e7eb" title="Lean Body Mass Calculator"></iframe>Free to embed. Attribution link included automatically.