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Pendum

FFMI calculator

Fat-free mass index is lean mass relative to height. Where BMI counts all of your weight, FFMI counts only what is not fat.

Input / Measurements

Your details

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Sex

From a scan, calipers or a tape-measure estimate.

Estimate body fat
Result / FFMIAdults

Result

No input

Enter your sex, height, weight and body fat to see your FFMI.

How it is calculated

Lean (fat-free) mass is your weight less its fat. FFMI divides it by the square of height, as BMI does with whole body weight. Pendum Body computes the same value as BMI × (1 − body fat % ÷ 100). Weight and lean mass are in kilograms, height in meters and BF is the body-fat percentage; imperial inputs are converted exactly (1 lb = 0.45359237 kg, 1 in = 2.54 cm) first.

lean       = weight × (1 − BF ÷ 100)
FFMI       = lean ÷ height²
normalized = FFMI + 6.1 × (1.8 − height)

FFMI rises slightly with height. Normalized FFMI, from Kouri et al. (1995), adjusts the value to a height of 1.8 m: it adds 0.061 for each centimeter under 1.8 m and takes off the same for each centimeter over it. The abstract of that paper prints the coefficient as 6.3; this calculator uses 6.1, the value in common use. From 1.55 to 2.05 m the two differ by 0.05 or less. In the same study, normalized FFMI among male athletes who had not used anabolic steroids reached a limit of 25.0.

The result is rounded to one decimal and compared with Pendum Body’s bands for the unadjusted FFMI: typical lean mass from 17.0 to 20.0 for men and from 14.0 to 17.0 for women, both ends included, with lower and higher lean mass on either side. These are simplified comparisons, not clinical cutoffs and not targets. For context, Schutz et al. (2002) found a median FFMI of 18.9 in men and 15.4 in women aged 18 to 34, in 5,635 white adults in Switzerland measured by bioelectrical impedance.

FFMI bands beside the Schutz medians

Pendum Body’s FFMI bands for men and women in kg/m², with the median FFMI at ages 18 to 34 from Schutz et al. (2002)
BandMenWomen
Lower lean mass< 17.0< 14.0
Typical lean mass17.0–20.014.0–17.0
Higher lean mass> 20.0> 17.0
Median, ages 18 to 3418.915.4

Unadjusted FFMI in kg/m², on the one-decimal value, both ends of the typical band included. The bands are Pendum Body’s simplified comparisons; the medians are for ages 18 to 34 in Schutz et al. (2002).

The band follows the one-decimal value, so the number and its word always agree. Pendum Body applies the same bands to the unrounded FFMI, so a result that rounds onto a band edge from outside can be named differently there. For a man, 20.04 shows as 20.0 and is typical here, and higher lean mass in the app.

FFMI is only as good as the body-fat figure behind it. An error of 3 points of body fat moves FFMI by about 0.7 for a person with a BMI of 24.

For adults. FFMI describes body composition; it is not a diagnosis, and the bands are not age-specific.

Sources

  1. Kouri EM, Pope HG Jr, Katz DL, Oliva P. Fat-free mass index in users and nonusers of anabolic-androgenic steroids. Clin J Sport Med, 1995;5(4):223–228.
  2. Schutz Y, Kyle UU, Pichard C. Fat-free mass index and fat mass index percentiles in Caucasians aged 18–98 y. Int J Obes Relat Metab Disord, 2002;26(7):953–960.

Method and sources checked on by Svindland Software LLC.

Help / FFMI

Common questions

How is FFMI calculated?

Lean mass is weight × (1 − body fat % ÷ 100), and FFMI divides it by height squared, in kilograms and meters. Pendum Body computes the same value as BMI × (1 − body fat % ÷ 100). Imperial inputs are converted exactly first.

What is a typical FFMI?

Pendum Body’s bands for the unadjusted FFMI call 17.0 to 20.0 typical lean mass for men and 14.0 to 17.0 for women, both ends included, with lower and higher lean mass on either side. They are simplified comparisons, not clinical cutoffs and not targets. For context, Schutz et al. (2002) found a median FFMI of 18.9 in men and 15.4 in women aged 18 to 34.

What is normalized FFMI?

An adjustment to a height of 1.8 m from Kouri et al. (1995): it adds 0.061 for each centimeter under 1.8 m and takes off the same for each centimeter over it. This calculator uses the coefficient 6.1, the value in common use; from 1.55 to 2.05 m it differs from the paper’s 6.3 by 0.05 or less.

Is there an FFMI limit for lifters who do not use steroids?

In Kouri et al. (1995), normalized FFMI among male athletes who had not used anabolic steroids reached a limit of 25.0. The number is only as good as the body-fat figure behind it: an error of 3 points of body fat moves FFMI by about 0.7 for a person with a BMI of 24.

Track / Offline

Pendum Body tracks it over time

One-time purchase, $9.99 once. No account.

Pendum Body computes FFMI from your trend weight and body-fat estimate and shows it on its dashboard with the same bands.

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