Lean Body Mass Calculator – Estimate Lean Body Weight
Split your weight into lean mass and fat mass.
About the Lean Body Mass Calculator
What is the Lean Body Mass Calculator?
A lean body mass calculator estimates how many kilograms of your weight are muscle, bone, organs and water rather than fat.
Why use this calculator?
Preserving lean mass during weight loss keeps your metabolism and strength intact, making LBM a better goal than weight alone.
How to use it
- Enter your gender, weight and height.
- Choose Boer (simplest) or the Navy-style formula.
- Read your lean mass and fat mass split.
Formula
Boer equations use weight and height; Navy approach derives body fat from circumference measures.
Estimates vary by several percent from scans. Use trends over time rather than a single reading.
Frequently Asked Questions
Why track lean mass not just weight?
Crash diets often lose muscle along with fat. Tracking LBM shows whether your loss is healthy.
What is a healthy range?
Typical LBM is 75–85% of body weight for women and 80–90% for men, but it depends on training history and body size.
Is this a medical diagnosis?
No. This tool provides general wellness information only. It is not a substitute for evaluation by a qualified healthcare professional.
Why do results differ from my doctor's measurements?
Clinical measurements use calibrated equipment and professional technique. Home estimates rely on formulas and self-reported values, so small differences are normal.
How often should I recalculate?
Recheck after meaningful changes such as weight gain or loss, a new workout routine, or every few months to track trends over time.
Do these formulas apply to everyone?
Most population formulas are less accurate for athletes, pregnant people, very young children and the elderly. Use them as a general guide.
Is this calculator free to use?
Yes. Every calculator on this site is completely free, with no hidden fees, no subscriptions and no limits on how many times you can use it.
How accurate are the results?
We use standard, widely accepted formulas and calculate in your browser using double-precision arithmetic. Results are rounded for readability, so treat them as reliable estimates rather than a guarantee. Real-world factors can vary the true figure.
Can I add this calculator to my own website?
Yes. Open this calculator page and use the "Add to your website" box in the sidebar to copy a ready-made iframe snippet, then paste it into any HTML page.
Does it work on a phone or tablet?
Yes. The layout is fully responsive, so it works on desktops, laptops, tablets and mobile phones, and every input adapts to touch screens.