FFMI (fat free mass index) is a formula to quantify muscle development based on your height, weight, and body fat.

With the FFMI calculator, you’ll find your fitness category. See how you compare to your friends and get tips to improve your score.

Please note, gym persona is intended to be a fun way to assess fitness level… don’t take it too personally!

What Is FFMI?

FFMI is similar to BMI (body mass index). Both categorize people based on height and weight.

But FFMI is generally more accurate for active people because it accounts for body composition. That means it’s a better tool for finding your ideal weight.

FFMI Scale for Men

For men, the FFMI scale generally ranges from 15 to 25. While it’s possible to exceed 25, it’s considered unlikely without the use of steroids.

FFMI Natural Physiques

One study compared 83 steroid users and 74 natural bodybuilders. They concluded that the standardized FFMI for natural athletes extended up to a well-defined limit of 25.0¹.

In addition, the average FFMI for Mr. America winners before 1960 is 25.4¹. This is assumed to be the pre-steroid era of bodybuilding (although that’s debatable).

Despite this data, it is possible to exceed 25 naturally. But it requires good genetics and years of hard work.

FFMI Scale For Women

For women, building muscle is more challenging so the scale ranges from 12 to 22. With anything over 22 considered unlikely without steroids.

Lean Mass & Height

Weight distribution is different for taller and shorter people. For that reason, FFMI is normalized to average height. Or about 5’11” for men and 5’4″ for women. You’ll see both numbers in the results section of the FFMI calculator.

Of course, the taller you are the more lean mass you can fit on your frame. So taller people weigh more at the same FFMI as shorter people.

The graphs below show the FFMI ranges for different heights.

What Is A Good FFMI?

When trying to define a good FFMI, it’s useful to look at a large population. One study sampled over 5,000 men and women and compiled their FFMI data².

I’ve plotted that data here in what’s called a normal distribution or ‘bell curve’. So you can see where the majority of people fall on the FFMI scale.

How to Improve FFMI

It’s important to consider body fat along with FFMI when determining how to improve your physique. Because you could have a high FFMI and not be in good shape.

For example, top-level sumo wrestlers are extremely muscular and have very high body fat levels. That’s useful for pushing opponents around, but it’s not the look most of us want.

Therefore, it’s a good idea to focus on reducing body fat if you’re in the overweight or obese categories.

7 Simple Steps To Get Shredded

The “Gym Persona” matrix is intended to make it easy to see which way to go. If you’re in the first two columns you should work on moving to the right.

Once you have your body fat under control, start gaining muscle in order to move down.

More On Muscle Gain Nutrition

At the end of the day, a “good” FFMI is only relative to your starting point. If you’re just beginning, don’t be intimidated by comparing yourself to others. Aim for incremental improvements and strive for your personal best.

Conclusion

FFMI is a useful tool for men and women to assess their current level of fitness. Compared to BMI it’s more accurate and representative of the active population.

In addition, FFMI can predict a naturally attainable goal for your frame. Which helps you determine how to adjust your diet and training to get there.

If you had fun with this FFMI calculator please share it with your friends. And check out my other free tools.

References:
1) Kouri, Elena M., et al. “Fat-free mass index in users and nonusers of anabolic-androgenic steroids.” Clinical journal of sport medicine: official journal of the Canadian Academy of Sport Medicine 5.4 (1995): 223-228.
2) Schutz, Y., U. U. G. Kyle, and C. Pichard. “Fat-free mass index and fat mass index percentiles in Caucasians aged 18–98 y.” International journal of obesity 26.7 (2002): 953-960.