Lean Body Mass & FFMI Calculator
Estimate lean body mass with the Boer formula (or from your body fat %) and your fat-free mass index (FFMI), normalized to 1.8 m.
For general information only — not medical advice. Results are estimates; talk to a doctor or qualified health professional about your own health.
How to use
- 1Enter your weight, height and sex.
- 2Optionally enter a measured body fat percentage for a more precise result.
How it's calculated
Boer: men LBM = 0.407W + 0.267H − 19.2; women 0.252W + 0.473H − 48.3 (kg, cm). With body fat: LBM = W × (1 − BF). FFMI = LBM ÷ height(m)²; normalized FFMI = FFMI + 6.1 × (1.8 − height).
Frequently asked questions
What's a typical FFMI?
Around 18–20 for untrained men and 15–17 for women. Values above about 25 are rarely reached without performance-enhancing drugs, according to a 1995 study.
Why normalize FFMI?
Taller people naturally carry more lean mass; the correction makes scores comparable across heights.
Which LBM estimate is better?
One based on a good body-fat measurement (DEXA, calipers or the Navy method) beats a height-and-weight formula.