Lean Body Mass Calculator

Estimate lean body mass from weight and body fat.

Lean body mass 64

Fat mass 16

Formula: LBM = weight × (1 − body fat%/100)

Step-by-step with your numbers:

1. Values used:

2. Weight = 80

3. Body fat = 20 %

5. Lean body mass = 64

6. Fat mass = (80 / 100) x 20 = 0.8 x 20 = 16

Did we solve your problem today?

Lean body mass is everything except fat — muscle, bone, organs and water.

The math behind it

LBM = weight − (weight × body fat% ÷ 100).

80 kg at 20% fat → 64 kg lean.

Why track it?

Preserving lean mass during weight loss keeps your metabolism higher.