Fat Free Mass Index
Scale measured fat-free mass by height squared.
Your numbers
FFMI
For personal measurement and planning, not diagnosis, treatment or a training prescription. Measurement error and individual differences affect results.
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Formula
Use FFMI = W(1−f)/h². W is body mass in kg, f is measured body fat as a fraction, and h is height converted to m. The index is in kg/m².
Scale measured fat-free mass by height squared.
Worked example
- Body mass (kg)
- 75
- Height (cm)
- 180
- Measured body fat (%)
- 20
- FFMI
- 18.5185 kg/m²
- Fat-free mass
- 60 kg
Scope and limitations
For personal measurement and planning, not diagnosis, treatment or a training prescription. Measurement error and individual differences affect results.
Inputs are checked for missing values and allowed ranges. A result outside the finite numeric range is not displayed. Rounding affects display, while the calculation uses the model’s numeric precision.
Check your units and assumptions before relying on a result. Changing a label does not convert a currency or physical unit.
Formula version: 54d0e6d1c6df · Example checked: