FFMI Formula
The Fat-Free Mass Index (FFMI) is a valuable metric that assesses the amount of lean body mass an individual possesses relative to their height, providing insight into muscularity and body composition.
Formula
Copy the exact expression or work through it step by step below.
FFMI = Lean Body Mass / Height In Meters ^ 2 Variables
FFMI
FFMI
The ffmi value plugged into the ffmi calculation.
LBM
Lean Body Mass
The lean body mass value plugged into the ffmi calculation.
HIM
Height In Meters
The height in meters value plugged into the ffmi calculation.
Step By Step
- 1
Set the baseline case with the real calculator inputs.
Weight Kg = 80, Height Cm = 178, Body Fat Pct = 15.0%
- 2
Translate rates, periods, and cash values onto the same footing before combining them.
Keep the ffmi assumptions consistent instead of mixing monthly and annual views.
- 3
Apply the formula and read the first calculator outputs, not just the headline assumption.
The calculator lands with ffmi at 21.46 and adjusted ffmi at 21.58.
- 4
Run one changed scenario so the formula is stress-tested before it is trusted.
The ffmi calculator page is the fastest way to compare that second case.
Worked Example
FFMI sample case
Weight Kg
80
Height Cm
178
Body Fat Pct
15.0%
FFMI = Lean Body Mass / Height In Meters ^ 2 using weight kg 80, height cm 178, body fat pct 15.0%.
The calculator lands with ffmi at 21.46 and adjusted ffmi at 21.58.
Common Variations
Try These Tools
Run the numbers next
Body Fat Percentage Calculator
Estimate body fat percentage using the U.S. Navy circumference method.
Lean Body Mass Calculator
Estimate lean body mass using Boer, James, Hume, and Peters formulas from height and weight.
Sources & References
- Fat-Free Mass Index in Male Bodybuilders – Is There an Upper Limit to Natural Muscularity? — National Center for Biotechnology Information (NCBI)
- The Fat-Free Mass Index: A New Standard for Body Composition Assessment — PubMed / Clinical Nutrition
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