Calculator · Performance Lab
FFMI Calculator
Compute your Fat-Free Mass Index and see honestly how muscular you are relative to your height.
Ergebnis
- Fat-free mass (FFM)
- 68.0kg
- FFMI
- 21.0
- Normalized FFMI
- 21.0
- Classification
- above average
Weight × (1 − body fat).
FFM / height².
Adjusted to 1.80 m height — the comparable figure.
Explained
What this calculator does for you
FFMI (Fat-Free Mass Index) measures muscularity, normalized to height. Unlike BMI, it separates fat from muscle — and is therefore the far more honest figure for athletes.
The 'normalized' FFMI additionally factors out height so values become directly comparable between small and tall people. That's the number quoted in discussions.
Accuracy lives and dies with your body-fat input. Estimate conservatively — guessing 10 % when reality is 15 % shifts FFMI by roughly a full point.
Science
Scientific background
FFM = weight × (1 − bf%/100). FFMI = FFM / height². Normalized FFMI = FFMI + 6.1 × (1.8 − height in m).
Reference (men): ~18–20 average · 20–22 above average · 22–23 very muscular · 23–25 near the discussed natural limit · >25 rare without pharmacology. Women correspondingly lower (~14–17 average · 17–19 athletic · 19–21 very muscular).
The '~25 limit' originates from Kouri et al. (1995) and is a popular heuristic — not a hard biological ceiling. Individual natural athletes demonstrably exceed it.
Examples
Practical examples
180 cm, 80 kg, 15 % bf, male
FFM ≈ 68 kg. FFMI ≈ 21.0. Normalized FFMI ≈ 21.0 — above average, well-developed training status.
168 cm, 60 kg, 22 % bf, female
FFM ≈ 46.8 kg. FFMI ≈ 16.6. Normalized FFMI ≈ 17.3 — athletic range for women.
Avoid these
Common mistakes
- 01Underestimating body-fat — that inflates FFMI artificially.
- 02Treating the natural limit as an absolute verdict instead of a heuristic.
- 03Confusing FFMI with BMI. BMI ignores body composition entirely.
- 04Measuring weekly and reacting to noise — monthly windows make more sense.
Recommendations
Further recommendations
- 01Use the body-fat calculator for an honest body-fat estimate and bring it here.
- 02Judge FFMI across months — muscle gain is slow, especially intermediate-and-up.
- 03Combine FFMI with strength figures (1RM calculator) for a complete picture of your development.
- 04Set realistic goals: +1 FFMI point per year is already strong for advanced lifters.
FAQ
Frequently asked questions
- Why is FFMI better than BMI?
- BMI treats muscle and fat equally. A muscular athlete often lands in 'overweight'. FFMI strips fat out and measures actual muscle relative to frame.
- How accurate must my body-fat be?
- Very. A 5-percentage-point error shifts FFMI by ~1 point. Use an honest figure (body-fat calculator, DEXA, BIA) — not an optimistic guess.
- Is FFMI > 25 always unnatural?
- No. It's a heuristic. Most people plateau between 24–25 naturally after many years — individuals go higher. Treat the line as an indicator, not a verdict.
- How do I grow FFMI sensibly?
- Long term: strength training + protein (~1.6–2.2 g/kg) + patience. Natural progression slows sharply after the first years.
- Does FFMI apply to women?
- Yes, with lower reference values. Very muscular women reach 19–21+.
More tools
Related tools
Body Fat Calculator
Estimate your body-fat percentage with the U.S. Navy circumference method — fast, no device, with clear classification.
BMI Calculator
Body-Mass-Index by WHO standard. A quick orientation — with an honest read on its limits.
Goal Weight Calculator
Sensible goal weight from a target body-fat percentage — more meaningful than BMI.
Knowledge Hub
More on this in the Knowledge Hub
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