FFMI Calculator

Fat-free mass index — how much muscle you carry for your height, with the height-normalised figure that the scales are actually built on.

Reference table

Weight	Normalised FFMI	What That Means	Raw FFMI (unadjusted)
30	8.2	Below average	8.0
40	10.9	Below average	10.7
50	13.5	Below average	13.4
60	16.2	Below average	16.1
70	18.9	Average	18.8
75	20.2	Above average	20.1
80	21.6	Above average	21.5
90	24.3	Superior — years of serious training	24.1
100	26.9	Beyond what is usually reached drug-free	26.8
150	40.4	Beyond what is usually reached drug-free	40.2
200	53.8	Beyond what is usually reached drug-free	53.7

📊 Normalised FFMI Bands

Male — below averageunder 18
Male — average18 to 20
Male — above average20 to 22
Male — excellent22 to 23
Male — superior23 to 26
Female — average to superior13 to 19

Reading the Number Honestly

The whole result rests on your body fat percentage. A five-point error there moves the FFMI by about a full point, which is a whole band.
Use the normalised figure for any comparison. The raw one is only comparable between people of exactly the same height.
Normalising helps shorter people and trims taller ones. At 1.65 m it adds about 0.9; at 1.90 m it subtracts about 0.6.
A high FFMI says you carry a lot of lean mass. Lean mass includes bone, organs and water, not only muscle, so it is not a muscle measurement on its own.

What It Fixes About BMI

BMI divides weight by height squared and has no way of knowing what that weight is made of, which is why a lean, heavily muscled person is routinely classified as overweight by it. FFMI performs the same division but strips the fat out first: fat-free mass is body weight times one minus your body fat fraction, and that is what gets divided by height squared. The result answers a different question — not how heavy you are for your height, but how much lean tissue you carry for your height. That makes it useful for anyone who lifts, and it is the reason the measure is far more common in gyms than in clinics. It also means the answer is only ever as good as the body fat figure you fed it, because that single number is doing all the work of separating muscle from everything else.

Why the Normalised Figure Is the Real One

Dividing by height squared does not fully cancel height. Lean mass scales with something closer to height cubed in practice, so the raw FFMI drifts downward for short people and upward for tall ones, and comparing two people of different heights on it is not a fair comparison. Kouri and colleagues addressed this in 1995 by normalising every reading to a 1.80 metre reference: add 6.1 times the difference between 1.80 and your actual height in metres. A person of 1.65 metres gains about 0.9 points, one of 1.90 loses about 0.6. Every published FFMI table — including the one on this page — is built on the normalised scale, so reading a raw FFMI against those bands understates short lifters and flatters tall ones. Both figures are shown here, and the large one is the normalised one.

The Natural Limit of 25, With the Caveats

The figure comes from Kouri et al. 1995, which measured 157 male lifters and found that none of the drug-free group exceeded a normalised FFMI of 25.
It is the most-cited number in the whole topic, and it is an observed ceiling in one sample — not a law of physiology.
The sample was small, male, and from one era of one sport. Treating it as a steroid detector is more than the study supports.
Reaching even 22 normalised takes years of consistent training for most men, so the interesting territory for nearly everyone is well below the limit.
Errors in body fat percentage push FFMI around by a point or more, which is enough to move someone across the line by measurement error alone.
Women were not in that sample. The female bands here are the commonly used scale, roughly three points below the male one, and rest on thinner evidence.

Getting a Body Fat Figure Worth Using

Skinfold calipers with a consistent operator are cheap and reproducible, which matters more than absolute accuracy when you are tracking change.
Bioimpedance scales swing with hydration by several points across a single day. Measure at the same time, in the same state, or not at all.
DEXA is the practical reference standard and is worth one scan if you want a real anchor for the cheaper methods.
Visual estimation charts are better than nothing and worse than everything else. Expect to be three to five points out.
Whatever method you pick, keep using the same one. A trend measured badly but consistently beats single readings measured well.
If you have no figure at all, work it out first rather than guessing — a guess propagates straight into the FFMI.

Worked Examples

Where normalising changes the reading

Male, 80 kg, 1.78 m, 15% fat

Fat-free mass = 80 × (1 − 0.15) = 68.0 kg
Raw FFMI = 68.0 ÷ 1.78² = 21.5
Normalised = 21.5 + 6.1 × (1.80 − 1.78) = 21.6

21.6 normalised — above average

Male, 70 kg, 1.65 m, 12% fat

Fat-free mass = 70 × 0.88 = 61.6 kg
Raw FFMI = 61.6 ÷ 1.65² = 22.6
Normalised = 22.6 + 6.1 × (1.80 − 1.65) = 23.5

Raw says 22.6; normalised says 23.5 — a band higher

Frequently Asked Questions

What is a good FFMI?

On the normalised scale, 18 to 20 is average for men, 20 to 22 above average, and 22 to 23 the range of someone who has trained seriously for years. For women the same descriptions sit about three points lower, roughly 13 to 15 average and 17.5 to 19 excellent. Anything is only meaningful next to an accurate body fat figure.

What is the difference between FFMI and normalised FFMI?

Raw FFMI is fat-free mass divided by height in metres squared. That division does not fully remove the effect of height, so it understates short people and flatters tall ones. Normalised FFMI adds 6.1 times the difference between 1.80 metres and your height, putting everyone on a common reference. Every published FFMI table is built on the normalised scale.

Is an FFMI of 25 really the natural limit?

It is an observed ceiling, not a physiological law. Kouri and colleagues measured 157 male lifters in 1995 and found none of the drug-free group above a normalised 25. That is a small, male, single-era sample, and body fat measurement error alone can move someone a full point. It is a useful reference point, not a steroid test.

Do I need my body fat percentage?

Yes, and it is doing most of the work. Fat-free mass is weight times one minus your body fat fraction, so a five-point error in body fat shifts the FFMI by about a point — a whole interpretation band. If you do not have a measured figure, get one before trusting the result rather than entering a guess.

Why does BMI call me overweight when my FFMI is fine?

Because BMI cannot see what your weight is made of. It divides total weight by height squared, so muscle and fat count identically. FFMI removes the fat first, which is exactly the distinction BMI is missing, and it is why the two can disagree sharply for anyone who lifts.

Does FFMI measure muscle?

Not exactly. It measures fat-free mass, which includes bone, organs, connective tissue and body water alongside muscle. Muscle is the part that changes most with training, so changes in FFMI over months largely reflect muscle — but a single reading is not a muscle measurement, and hydration alone can move it.