FFMI Calculator
Calculate Fat-Free Mass Index (FFMI) — the gold standard for assessing muscularity in athletes and lifters.
What is FFMI?
FFMI normalises lean mass for height the same way BMI normalises total weight. It rewards muscle and ignores fat, which makes it far more meaningful than BMI for trained populations. Untrained men typically score 16–18; well-trained natural lifters reach 22–24; values above 25 in a male without a very tall build are unusual without anabolic-enhancement.
How is it calculated?
FFMI = LBM (kg) / height (m)². Adjusted FFMI = FFMI + 6.1 × (1.8 − height in m), which corrects for the under-estimation in tall lifters. LBM is computed from weight and body-fat percentage: LBM = weight × (1 − body-fat%/100).
Frequently Asked Questions
- What is a good FFMI?
- 16–18 untrained, 19–21 recreational, 22–24 advanced natural, >25 unusual without enhancement.
- How do I get my body-fat percentage?
- DEXA, calipers, or our Body Fat calculator.
- Does FFMI apply to women?
- Yes, but female norms are roughly 4 points lower than men.