Free calculator
FFMI Calculator
Estimate fat-free mass index from height, weight and body-fat percentage.
What FFMI shows
FFMI compares lean mass to height. It can give more context than body weight alone because two people at the same weight may have very different lean mass and body-fat levels.
The estimate depends heavily on the accuracy of body-fat percentage. If body-fat input is wrong, FFMI will also be wrong.
How to interpret it safely
Do not use FFMI as a self-worth score. It is a rough body-composition metric. Strength, health, energy, recovery and consistency matter more than chasing one number.
Related tools and guides
FFMI Calculator FAQs
Is this medical advice?
No. This is general information only.
How should I use the result?
Use it as a starting point and adjust based on real results and qualified advice where needed.
Why do calculator results differ?
Different formulas use different assumptions. Real-world tracking matters more than one estimate.