Unlike BMI, FFMI separates muscle from fat. Values above about 25 are uncommon in men without performance-enhancing drugs, according to a 1995 study.
How to use the FFMI Calculator
- Weight
- Height
- Body fat
Results update as you type, and every field accepts the units shown in its menu.
How it works
Remove fat mass from weight, then divide by height in metres squared.
Inputs explained
| Field | What to enter |
|---|---|
| Weight | Units: kg, lb, g, oz, st |
| Height | Units: cm, m, mm, in, ft |
| Body fat | In % |
What each result means
- Fat-free mass = [Weight] × (1 – [Body fat]÷100)
- FFMI = [Fat-free mass] ÷ ([Height]÷100)^2
- Normalised FFMI = [FFMI] + 6.1×(1.8 – [Height]÷100)
Example values
How the main result changes when Weight changes and everything else stays at the example values above:
| Weight (kg) | Normalised FFMI |
|---|---|
| 41 | 10.8 |
| 61.5 | 16.1 |
| 82 | 21.5 |
| 102.5 | 26.9 |
| 123 | 32.3 |
| 164 | 43 |
Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.
Formula
Fat-free mass = W × (1 − BF%)FFMI = FFM ÷ height²Normalised FFMI = FFMI + 6.1 × (1.8 − height m)Worked example
Inputs — Weight: 82 kg; Height: 180 cm; Body fat: 15 %.
Results — Fat-free mass = 69.7 kg; FFMI = 21.5; Normalised FFMI = 21.5.
Frequently asked questions
What is a typical FFMI?
Around 18–20 for untrained men and 14–17 for untrained women.
How do I get body fat %?
Use the body fat calculator or a body composition scan.
What formula does the FFMI Calculator use?
Fat-free mass = W × (1 − BF%).