Lean Body Mass Calculator (FFMI)
Enter your height, weight and circumference measurements to see your lean mass, body fat percentage and FFMI score.
Enter height and circumferences in centimetres (cm) and weight in kilograms (kg).
This tool is for information only and does not replace a doctor. Body fat is estimated from circumference measurements and may differ by ±3–5% from clinical methods such as DEXA or hydrodensitometry.
Why Does LBM Matter?
When losing weight, the aim is to lose fat while keeping lean mass (muscle). Knowing your LBM helps you work out protein and daily calorie needs more accurately. The higher your LBM, the more calories you burn at rest.
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 approach with the most evidence combines resistance training 3–4 times a week, 1.6–2.2 g/kg of protein a day and 7–9 hours of sleep.