FFMI Calculator
Fat free mass index with the height-normalised adjustment.
Enter your values
Enter the body weight in kg.
Enter the height in cm.
Enter the body fat in %.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Adjusted FFMI
- 21.58
- Raw FFMI
- 21.46
- Lean body mass
- 68 kg
- Fat mass
- 12 kg
- Rating
- above average
Working
- 1lean 68 kg / 1.78^2 = 21.46
- 2adjusted = 21.46 + 6.1 x (1.8 - 1.78) = 21.58
Quick answer
FFMI is lean mass in kilograms divided by height in metres squared. It rates muscularity independently of fat, and around 25 adjusted is the usual natural ceiling.
FFMI = lean kg / height m^2; adjusted = FFMI + 6.1 x (1.8 - height m)
At a glance
| What it does | Fat free mass index with the height-normalised adjustment. |
|---|---|
| Category | Fitness |
| Inputs needed | Body weight, Height, Body fat |
| Main output | Adjusted FFMI |
| Formula | FFMI = lean kg / height m^2; adjusted = FFMI + 6.1 x (1.8 - height m) |
| Cost | Free — no sign-up, no download |
How to use the FFMI Calculator
- 1Enter your weight and height, then your best body fat estimate (calipers, DEXA or a scan).
- 2Read the adjusted FFMI, which corrects for being taller or shorter than 1.8 m.
- 3Track it over months — FFMI moving up while body fat holds flat means real muscle gain.
Inputs explained
- Body weight(kg)
- Enter the body weight in kg.
- Height(cm)
- Enter the height in cm.
- Body fat(%)
- Enter the body fat in %.
Worked example
Using the values the calculator loads with:
Inputs
- Body weight80 kg
- Height178 cm
- Body fat15 %
Results
- Adjusted FFMI21.58
- Raw FFMI21.46
- Lean body mass68 kg
- Fat mass12 kg
- Ratingabove average
- lean 68 kg / 1.78^2 = 21.46
- adjusted = 21.46 + 6.1 x (1.8 - 1.78) = 21.58
Frequently asked questions
What FFMI is achievable naturally?
Most drug-free lifters top out around 22 to 25 adjusted FFMI. Values above 26 are uncommon without exceptional genetics.
Why does body fat accuracy matter so much?
FFMI is driven entirely by lean mass, so a body fat estimate that is 5 points off will shift FFMI by roughly one full point.
What do I need to enter into the FFMI Calculator?
Just 3 values: body weight, height, body fat. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the FFMI Calculator work out the answer?
FFMI is lean mass in kilograms divided by height in metres squared. It rates muscularity independently of fat, and around 25 adjusted is the usual natural ceiling. It applies the formula FFMI = lean kg / height m^2; adjusted = FFMI + 6.1 x (1.8 - height m) and shows the working so you can check each step by hand.
Is the FFMI Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.