💪Lean Body Mass Calculator

Calculate lean body mass from weight and body fat percentage.

Total Body Weight (lbs)

Body Fat Percentage (%)

About Lean Body Mass Calculator

Calculate your lean body mass (LBM) — the total weight of everything in your body except fat — from your total weight and body fat percentage. LBM includes muscle, bone, organs, and water. Knowing your lean mass is essential for setting precise protein targets, calibrating calorie intake during a cut or bulk, and tracking true muscle gain over time.

How to Use Lean Body Mass Calculator

1
Step 1
Enter your total body weight in pounds or kilograms.
2
Step 2
Enter your body fat percentage (use our Body Fat Calculator if you don't know it).
3
Step 3
View your lean body mass, fat mass, and the ratio between them.

Common Use Cases

Setting precise daily protein targets based on lean mass rather than total weight
Tracking whether weight changes during a diet are from fat loss or muscle loss
Calculating calorie needs using lean mass-based TDEE formulas
Monitoring lean mass retention and growth during strength training programs

Frequently Asked Questions

Why is lean body mass important?

LBM is a more meaningful metric than total body weight for fitness purposes because it shows how much muscle and structural tissue you have. It's used to set protein targets, calculate drug dosing in clinical settings, and evaluate body composition changes more accurately than scale weight alone.

What is the difference between lean body mass and fat-free mass?

Lean body mass includes a small amount of essential fat (around 3% in men and 12% in women) that surrounds organs and the nervous system. Fat-free mass excludes all fat entirely. The terms are often used interchangeably in fitness contexts.

How should I measure body fat percentage for the most accurate result?

DEXA scan is most accurate, followed by hydrostatic weighing, skinfold calipers, and the Navy tape measurement method. Bioelectrical impedance (bathroom scales with BIA) is convenient but less accurate.