Fat-Free Mass Index (FFMI) Calculator
Estimate lean body mass and compare muscularity across heights using FFMI. Normalized FFMI adjusts for height to make fair comparisons.
Inputs
Use a reliable scale, body fat measurement, and height measurement for best results.
FFMI Results
FFMI
20.99
Unadjusted for height.
Normalized FFMI
20.99
Adjusted to 1.80 m (5′11″) per Kouri et al.
Lean body mass
68.0 kg (149.9 lb)
Interpretation
Athletic build with solid lean mass.
Body fat mass
12.0 kg (26.5 lb)
Converted measurements
Height: 1.80 m (70.9 in) • Weight: 80.0 kg
How to Use This Calculator
Get body composition data
Use skinfold calipers, DEXA, or a bioimpedance scale to estimate body fat percentage. Consistency of method is key.
Enter current stats
Provide accurate weight and height. The calculator converts imperial inputs to metric to compute FFMI.
Compare to norms
Evaluate how your FFMI stacks up against population and athletic benchmarks. Use normalized FFMI for fair comparisons across heights.
Formula
FFMI = Lean Body Mass (kg) ÷ Height² (m²)
Normalized FFMI = FFMI + 6.1 × (1.8 − Height)
- Lean Body Mass (kg) = Weight (kg) × (1 − Body Fat % ÷ 100)
- Normalization adjusts FFMI to a reference height of 1.80 m, based on Kouri et al. 1995.
- A normalized FFMI above ~25 is rare without advanced training or ergogenic aids.
All inputs are converted to metric units before calculation.
Understanding FFMI
FFMI quantifies the amount of muscle relative to height, offering an objective look at muscular development. Normalized FFMI accounts for height differences, enabling fair comparisons between shorter and taller individuals.
Track FFMI over time to monitor lean mass changes during bulking, cutting, or recomposition phases. Pair with strength metrics and health markers for a comprehensive view.
Frequently Asked Questions
What is a good FFMI?
An FFMI between 19–21 is typical for recreational lifters. Values above 23 indicate advanced muscularity; above 25 is elite.
How accurate is body fat measurement?
FFMI accuracy depends heavily on body fat estimates. Use the same method consistently to track trends even if absolute numbers vary.
Does FFMI replace BMI?
No. BMI is a general population screening tool. FFMI is specific to body composition and fitness contexts.
Can women use FFMI?
Yes. FFMI applies to all genders, but typical ranges differ. Women often have lower FFMI due to higher essential body fat.