Lean Body Mass Calculator (FFMI)
Calculate your body fat percentage and FFMI score using your height, weight and circumference measurements.
Enter all measurements in centimetres (cm) or kilograms (kg).
This tool is for informational purposes only. Body fat percentage is estimated via circumference measurements and may deviate ±3–5% compared to clinical methods such as DEXA or hydrodensitometry.
Why Does LBM Matter?
Lean body mass (LBM) is the body's metabolic engine. The higher the LBM, the more calories burned at rest. Beyond this, LBM determines bone density, immune function, and long-term functional capacity.
Calculation Methods: Boer, James and Hume
The Boer, James and Hume formulas used for LBM calculation each employ different anthropometric variables. This tool uses the widely accepted US Navy circumference method.
Increasing Lean Body Mass
The most evidence-based approach for LBM gain is a triple combination: resistance training 3–4 times per week, 1.6–2.2 g/kg protein intake daily, and adequate sleep (7–9 hours).