Fat Free Mass Index (FFMI) Calculator [lb/kg]

People tend to focus a lot on their overall weight. However, research studies indicate that body composition might be the more effective metric for evaluating one’s health and fitness levels ^[1]. One of the best and most accurate ways of doing this is to measure your fat-free mass index (FFMI). You can get a precise value by using our comprehensive FFMI calculator.

What is my FFMI?

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The fat-free mass index calculator has many applications. It can aid your bodybuilding journey by giving you a concrete idea of your body composition. Based on the reading, you can alter your programs to either lose fat or gain more muscle.

Moreover, it also has many health-based benefits. Excessive fat can lead to obesity, which can cause medical issues like high blood pressure, type-2 diabetes, depression, heart disease, and more ^[2]. You can monitor your FFMI score regularly to ensure that you stay within the “healthy” range at all times.

It wasn’t always this easy to calculate FFMI precisely. The value depends on various factors, including your weight, height, body fat percentage, and even gender.

Men always have more muscle mass and less body fat compared to women. Studies explain that this predisposition is because women need more body fat to support functions like childbirth and menstruation ^[3]. 

Because of all these varying factors, the FFMI scale would look different for each individual, irrespective of the similarities in their lifestyle. Without our calculator (or expensive clinical tests), it would be impossible for bodybuilders to know their fat-free body weight precisely.

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What is FFMI?

FFMI, or Fat-Free Mass Index, is the measure of an individual’s muscle mass relative to their height. It takes into account many variables like height, body fat percentage, and sex to calculate a person’s fat-free mass.

FFMI can be used for programming better workout/nutrition programs or to mitigate the risk of obesity or malnutrition. It is, however, more commonly used in the bodybuilding realm to compare the progress of two or more fitness enthusiasts.

FFMI Formula

The FFMI formula provides more precise values compared to other similar indicators. That’s because the equation takes into account all the detriments or influencing factors.

To calculate your FFMI, you need to follow a two-step process.

1. Lean Weight (Kilograms) = Total Body Weight × (100% – Body Fat)
2. FFMI = Lean Weight (Kilograms) / Height (Meters)²

Using this formula, you can easily calculate your FFMI.

FFMI Scale

The FFMI scale provides a reference point for men and women to figure out where they stand.

If you are within the “healthy” or “normal range”, then it’s a good thing. On the other hand, if you find yourselves on either of the extreme ends of this scale, then you need to work hard to get to the optimal level.

Naturally, the scale differs for men and women.

FFMI Scale for Men

FFMI Scale for Women

FFMI Percentiles

Calculating FFMI values is all about figuring out if you’re better or worse than the average or healthy. While the exact index values are good for one-on-one comparisons, percentiles are better if you want to compare yourself against a sample or population.

The following table is based on a sample-based study ^[4].

FFMI Percentiles for Men

FFMI Percentiles for Women

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What’s the Difference Between FFMI and BMI?

Both FFMI and BMI (Body Mass Index) are measures of an individual’s body composition relative to their height. However, there are some major differences between them based on the variables they take into account.

BMI follows a relatively simpler calculation model. It only accounts for a person’s weight and height to provide a general indication of how far the person is from achieving the “ideal” body weight.

However, BMI readings are not as efficient because they don’t take into account the differences between fat and muscle mass. As such, athletes and people with high muscle mass cannot rely too much on their Body Mass Index readings.

FFMI, on the other hand, takes into consideration body fat percentage and sex to provide more precise, practical values.

Is FFMI Better than BMI?

Yes, most people (researchers included) feel that FFMI is a better indicator of an individual’s fitness level compared to BMI. That is because BMI is only efficient for the general population ^[5]. Apart from that, it does not do anything to provide information about fat-free mass and fat mass ^[6].

To help you understand, a well-built bodybuilder might record a higher value on the BMI scale as muscle is heavier than fat tissues. Because of this, they might record a BMI scale of over 25 and be classified as overweight ^[7].

The reality, however, is that the bodybuilder is in top shape and faces no risk of being overweight or obese.

In this regard, FFMI is better. It takes into account body fat percentage and provides a precise reading based on that information.

What is Normalized FFMI?

Normalized FFMI, often abbreviated as nFFMI, is a variation of the Fat-Free Mass Index that adjusts the calculation to account for the varying height differences among the general population.

nFFMI is basically used to adjust the FFMI readings of people who are taller than normal, especially more than 1.8 meters (for men) and 1.63 meters (for women).

Normalized values give more practical and fair indications. They are often used in the realms of sports and bodybuilding to identify potential cases of steroid use or other performance-enhancing substances.

Normalized FFMI Formula

Normalized FFMI is adjusted to account for extreme height differences within the sampled population.

For normalization, the FFMI formula is adjusted slightly.

• Normalized FFMI for Men = FFMI + 6.1 × [1.8 – Height(in meters)]
• Normalized FFMI for Women = FFMI + 6.1 × [1.63 – Height (in meters)]

What’s the Difference Between FFMI and Normalized FFMI?

FFMI and nFFMI are often used interchangeably and give similar readings. However, they are based on some prominent differences.

The simple FFMI formula has one limitation it inherited from the Body Mass Index (BMI) equation. The formula does not scale correctly with extreme variations in height.

To fix that, Normalized FFMI attempts to use linear regression and scales FFMI readings based on height differences.

What is a Good FFMI Score?

If you are looking for a good, healthy FFMI score, you should aim for anywhere between 17 and 20 if you are a female.

For men, an FFMI score between 20 and 23 can be considered above average and good compared to the rest of the population.

While these are not the most “excellent” values, they serve as realistic starting points for ambitious fitness enthusiasts.

Ideally, if you are a professional bodybuilder or athlete, you can aim for even more and go beyond this point.

What is the Highest Natural FFMI?

Many studies have been conducted to find out if there is a threshold or ceiling for natural FFMI. Unfortunately, the results have been largely inconclusive and are still up for further investigation.

Based on most studies, however, we can say that 25 is the limit beyond which going further naturally is very difficult ^[8].

But many researchers refute this conclusion and say that there is no fixed upper-ceiling for natural FFMI readings.

What is the Average FFMI for Men?

According to the generally accepted FFMI scale, the average value for men lies between 18 and 20.

Getting an FFMI score less than this indicates that you are skinny and lack adequate muscle mass. A value of more than 20 reveals that you have more muscle mass and potentially lesser body fat percentage.

What is the Average FFMI for Women?

For women, the average FFMI values are slightly lower. It is normal for a female to have an FFMI value between 14 and 17.

Anything less than this indicates that the women face the risk of being severely underweight. As we move further away from 17 to the right, body fat percentage decreases.

What FFMI Indicates Steroid Use?

Generally, studies indicate that an FFMI value over 25 indicates potential steroid usage. However, not everyone agrees as there have been instances of sportspeople and athletes who have gone beyond this value naturally.

Having an FFMI reading beyond 26 raises more suspicion and warrants drug tests to confirm the results.

Is FFMI Really a Good Indication of Steroid Usage?

Yes, FFMI is a really good indicator of steroid usage. While it does not provide any conclusive evidence for the same, it can help detect potential steroid usage or performance-enhancing drug abuse among athletes and sportspeople.

An FFMI value of above 25 may mean potential steroid usage. Based on this information, further investigation and tests can be carried out to confirm the suspicions.

Winding Up

FFMI is one of the best indicators of an individual’s health and fitness levels. It can be used for bodybuilding as well as for keeping track of one’s well-being.

Compared to BMI, Fat-Free Muscle Index can offer more practical and fair values.

References

1. Duren, D. L., Sherwood, R. J., Czerwinski, S. A., Lee, M., Choh, A. C., Siervogel, R. M., & Chumlea, W. C. (2008). Body Composition Methods: Comparisons and interpretation. Journal of Diabetes Science and Technology, 2(6), 1139–1146. https://doi.org/10.1177/193229680800200623
2. Köksal, Ü. İ., Ertürk, Z., Köksal, A., Özşenel, E. B., & Harmankaya, Ö. (2017). What is the Importance of Body Composition in Obesity-related Depression? The Eurasian Journal of Medicine, 49(2), 102–106. https://doi.org/10.5152/eurasianjmed.2017.16129
3. Frisch, R. E. (1987). Body fat, menarche, fitness and fertility. Human Reproduction, 2(6), 521–533. https://doi.org/10.1093/oxfordjournals.humrep.a136582
4. Schütz, Y., Kyle, U., & Pichard, C. (2002). Fat-free mass index and fat mass index percentiles in Caucasians aged 18–98 y. International Journal of Obesity, 26(7), 953–960. https://doi.org/10.1038/sj.ijo.0802037
5. World Health Organization: WHO. (2022). Nutrition EURO. euro.who.int. http://www.euro.who.int/en/health-topics/disease-prevention/nutrition/a-healthy-lifestyle/body-mass-index-bmi
6. Kyle, U. G., Schütz, Y., Dupertuis, Y., & Pichard, C. (2003). Body composition interpretation. Nutrition, 19(7–8), 597–604. https://doi.org/10.1016/s0899-9007(03)00061-3
7. Nuttall, F. Q. (2015). Body mass Index. Nutrition Today, 50(3), 117–128. https://doi.org/10.1097/nt.0000000000000092
8. Fat-Free mass Index in users and nonusers of. . . : Clinical Journal of Sport Medicine. (n.d.). LWW. https://journals.lww.com/cjsportsmed/Abstract/1995/10000/Fat_Free_Mass_Index_in_Users_and_Nonusers_of.3.aspx