Health Logo. FFMI Calculator

Fat Free Mass Index Calculator.

FFMI is an alternative to body mass index which accounts for a person's muscle mass. The average male scores about 19 and it is hard to score above 25 without using steroids or other banned substances.


Height & Weight Values
Height feet inches
Weight pounds
Body fat %
Your Results Values
Fat-free mass pounds
Body fat pounds
Normalized FFMI


Height & Weight Values
Weight kilos
Height meters
Body fat %
Your Results Values
Fat-free mass kilos
Body fat kilos
Normalized FFMI

Mathematical Formulas to Calculate FFMI

Total Body Fat Formula

  • Metric: Total Body Fat = Weight in Kg * (body fat % / 100)
  • English: Total Body Fat = Weight in lb * (body fat % / 100)

Lean Body Weight Formula

  • Metric: Lean Weight = Weight in Kg * (1 - (body fat % / 100)
  • English: Lean Weight = Weight in lb * (1 - (body fat % / 100)

FFMI Formula

  • Metric: FFMI = (Lean Weight in Kg / 2.2) * 2.20462 / ((meters) 2
  • English: FFMI = (Lean Weight in lb / 2.2) / ((Feet * 12.0 + Inches) * 0.0254)2

Adjusted FFMI Formula

  • Metric: Adjusted FFMI = FFMI + ( 6.1 * (1.8 - (meters))
  • English: Adjusted FFMI = FFMI + ( 6.1 * (1.8 - (Feet * 12.0 + Inches) * 0.0254))

Fat Free Mass Index: Importance and Maintaining the Right Levels

- Guide Authored by Corin B. Arenas, published on October 12, 2019

Normal body composition is vital for overall health. That's why maintaining balanced body fat levels is associated with a longer, disease-free life.[1]

Excessive fat, or anything that alters normal body composition, is heavily linked to conditions such as high blood pressure, type 2 diabetes, heart disease, and even obesity-related depression.[2]

In this section, you'll learn about the fat free mass index, it's significance in achieving a strong and healthy physique, and how it benefits professional athletes through the years.

What is the Fat Free Mass Index (FFMI)?

Muscular man powerlifting

FFMI is an alternative to body mass index which accounts for a person's muscle mass. The average male scores about 19 and it is hard to score above 25 without using steroids or other banned substances.

FFMI is conceptually similar to Body Mass Index (BMI). But instead of measuring body mass in relation to height, it measures the amount of muscles (fat-free mass) relative to a person's height.

This indicator accounts for the amount of total lean muscle mass in the body. Research also suggests it can predict how much muscle your body can potentially gain.

It's a useful indicator for people who are trying to lose weight, specifically those engaging in strength training to develop muscles and reduce body fat. FFMI is especially handy for serious body building enthusiasts.

What's the standard FFMI levels for men and women? See the tables below.

FFMI Ranges for Men

Description FFMI Range Body fat percent
Skinny guy 17-18 10-18
Typical average guy 18-20 20-27
Fat guy 19-21 25-40
Athlete / regular gym user 20-21 10-18
Advanced gym freak 22-23 6-12
Elite strength athlete (bodybuilders, etc.) 24-25 8-20

FFMI Ranges for Women

Description FFMI Range Body fat percent
Skinny woman 14-15 20-25
Typical average woman 14-17 22-35
Fat woman 15-18 30-45
Athlete / regular gym user 16-17 18-25
Advanced gym freak 18-20 15-22
Elite strength athlete (bodybuilders, etc.) 19-22 15-30

Why is it Different for Men and Women?

Muscular man and woman

This is because body composition varies between men and women.

According to the National Health Services (NHS), men biologically possess less body fat, more muscle mass, and greater bone density compared to women.[3] Women, on the other hand, naturally have more body fat to maintain their menstrual cycle and support childbirth.[4]

Unwanted Stolen Selfie Returned to Original Owner.

Females tend to develop adipose tissue, which is loose connective tissue composed of fat,[5] around their hips and thighs. Men, on the other hand, commonly accumulate adipose fat around the trunk of their body and abdomen.

The table below shows men and women's FFMI scores with their corresponding percentile. Basically, the higher your percentile, the leaner body mass you have.

FFMI by Percentile

Percentile Men Women
95% 22 18.5
90% 21 18
75% 20 17
50% 19 16

This contrast is made apparent in bodybuilding. In 1989, research published in the Journal of Applied Physiology showed difference in muscle fibers between elite male and female bodybuilders.[6]

In the study, they found that the cross-sectional area of biceps were 2 times greater in male bodybuilders compared to female bodybuilders. This result strongly correlated with lean body mass. The biceps developed per (kg) lean body mass was also 35% higher in men compared to women.

How is FFMI Different from BMI?

BMI is regarded as a good body mass indicator for the general population.[7] However, if you have more muscle than the average person, it does not distinguish fat from muscle. It only accounts for total body weight in comparison to height.

A 2003 study published in Nutrition found that BMI alone cannot provide information about fat-free mass or fat mass to body weight.[8]

What are its implications? This means lean athletes score high in the BMI scale despite not being obese or overweight.

For instance, two men may weigh 180 lbs. with the same height at 5″10. However, if you compare their bodies, one person is ripped with chiseled abs, while the other looks plain with a bulging midsection.

If you calculate their BMI, it comes out as 25.83, which is overweight according to the National Institutes of Health (NIH).[9]

The numbers may be the same, but the physical difference is striking. Moreover, it shows achieving an aesthetic physic requires muscle and strength training to literally get in shape.[10]

Here, BMI automatically assumes individuals gain weight from fat. In this case, it becomes a negative health indicator. Therefore, FFMI is a better measuring tool for lean and active people.

The Importance of Healthy Fat-Free Mass (FFM)

Man watching TV

Fat-free mass is a component which not only considers muscles and connective tissue. It includes bones, internal organs, and water content in the body.[11] The opposite of FFM is fat mass (FM), which accounts for adipose tissue, otherwise known as body fat.

Fat mass can be classified under 2 categories:

  • Essential fat – These are fats that cannot be produced by the body. They're essential for primary functions like brain development and blood clotting. Men need 2%-5% essential fats, while women require 10%-13% for a healthy body.
  • Non-essential fat – These are fats not needed for primary functions. It insulates the body and protects internal organs.

Basically, your body needs just the right amount of fat to keep it healthy. Athletes have low body fat which helps them perform at their peak. Lower body fat is the outcome when professional athletes train to reach optimum fitness.

The American Council on Exercise (ACE) published the following body fat chart according to different fitness levels.[12]

Classification Men % Body Fat Women % Body Fat
Essential fat 2 – 5% 10 – 13%
Athletes 6 – 13% 14 – 20%
Fitness 14 – 17% 21 – 24%
Average 18 – 24% 25 – 31%
Obese 25% and higher 32% and higher

High Muscle Mass in Sumo Wrestlers

Sumo Wrestlers

In a related study titled Body Composition and Isokinetic Strength of Professional Sumo Wrestlers, researchers found that some sumo wrestlers have exceptionally high FFMI scores which can significantly exceed normal ranges.[13]

The study examined how profiles of body composition and force generation capability manifested in sumo wrestlers. It included 23 low to high ranking sumo wrestlers, 21 weight classified athletes, and 21 untrained men. The table below provides a range of the participants' body composition.  

Men's Body Composition Range

Ranges Low High
Fat-Free Mass (FFM) 59.1 kg 107.6 kg
Relative Fat Mass 1.9% 37.0%
Body Mass Range 77 kg 150 kg
Body Mass Index 25.9 kg·m−2 44.5 kg·m−2

Researchers found that the median value of FFM relative to body height for higher-division Sumo wrestlers ranked high among previously reported data on heavyweight athletes.

If anything, the study shows it's possible to develop a high percentage of lean mass despite a lot of fat.

FFMI in Relation to Prevalent Use of Steroids

Super bulky body builder

In the last 30 years, illegal steroid use has become common practice in sports. To discourage performance enhancers, researchers came up with drug tests and ways to determine its use.

In 1995, scientists published a study in the Clinical Journal of Sport Medicine titled Fat-Free Mass Index in Users and Nonusers of Anabolic-Androgenic Steroids.[14] They claimed that analyzing FFMI can reveal if a person may be taking steroids for muscle enhancement.

The research uses information from the pre-steroid era to establish a baseline on possible steroid usage among modern athletes and bodybuilders.

It included 157 male athletes, with 83 steroid users and 74 non-users. Researchers found that many of the steroid users easily exceeded FFMI of 25, with some more than 30. While it's possible to reach FFMI levels of 25 naturally, this limit can easily be exceeded with the use of steroids.

The findings suggested that athletes with FFMI higher than 25 are highly likely to use steroids.

However, not everyone agrees that FFMI levels is a good predictor of steroid use. For one, bodybuilders may still be juicing even if their FFMI does not exceed 25.

Lyle McDonald, the fitness coach and researcher behind, argues that around 30 athletes in history have crossed the FFMI threshold without steroid use.[15] However, he also mentions that anabolics have been in use since the 1940s, bringing most of the Mr. America winners into question.

Fat-free mass index in users and nonusers of anabolic-androgenic steroids uses information from the pre-steroid era to establish a baseline on likely steroid usage among modern athletes and bodybuilders.

The table below includes the performance of Mr. America winners from before the steroid era to some current athletes.  

Name Year Adjusted FFMI Height Weight Claim to Fame
Bert Goodrich 1939 24.3     Mr. America winner
Roland Essmaker 1939 22.6     Mr. America winner
John Grimek 1940 24.0 5 ft 8.5 in 185 lbs. Mr. America winner
John Grimek 1941 26.9 5 ft 8.5 in 185 lbs. Mr. America winner
Frank Leight 1942 25.5     Mr. America winner
Jules Bacon 1943 23.9     Mr. America winner
Steve Stanko 1944 27.3 5 ft 11 in 223 lbs. Mr. America winner
Clarence Ross 1945 26.1     Mr. America winner
Alan Stephen 1946 25.9     Mr. America winner
Steve Reeves 1947 23.0     Mr. America winner
George Eiferman 1948 27.7     Mr. America winner
Jack Delinger 1949 28.0     Mr. America winner
John Farbotnik 1950 26.5     Mr. America winner
Roy Hilligenn 1951 26.0     Mr. America winner
Jim Park 1952 N/A     Mr. America winner
Bill Pearl 1953 25.8 5 ft 9 in to 10 in 201 to 242 lbs. Mr. America winner
Dick DuBois 1954 25.4     Mr. America winner
Steve Klisanin 1955 23.5     Mr. America winner
Ray Schaeffer 1956 N/A     Mr. America winner
Ron Lacy 1957 25.2     Mr. America winner
Tom Sansone 1958 26.8     Mr. America winner
Harry Johnson 1959 24.6     Mr. America winner
Mean of Mr. America winners 1939-59 25.4 +/- 1.5      
Barry Bonds 2001 28 6 ft 2 in 228 lbs. Home run king
Alex Rodriguez   26.4 6 ft 1.5 in 229 lbs. Baseball player
Jose Canseco   26.8 6 ft 4 in 240 lbs. Baseball player
Roger Clemens   26.0 6 ft 4 in 236 lbs. Baseball player, pitcher
Arnold Schwarzenegger 1974 28.5 6 ft 2 in 236 lbs. Mr Olympia, actor

Apart from bodybuilding, illegal steroid use is seen in all types of sports. Here are a few examples.

John Romano and Anthony Roberts are certified crossfit instructors behind who have discussed the issue openly in their site.[16]

Seven-time baseball MVP Barry Bonds has gone under question for illegal steroid use. An article in Reuters mentions photos of Bonds in 1991 at a lean 185 lbs., ballooning to 228 lbs. in 2001—the time when he hit a record of 73 home runs.[17]   

The following are examples of books on baseball and how it's mired with steroid scandals:

The Bottom Line

Achieving balanced FFMI levels is beneficial for both men and women, especially to athletes.

It is also a useful tool that can detect illegal steroid use. However, it is not the most accurate way to prove whether bodybuilders and other athletes have used performance enhancers.

While BMI is the standard indicator for body mass, FFMI is a better tool for tracking fat loss and overall improvement in muscle development.

About the Author

Working as a health writer since 2016, Corin is interested in longevity research and how to improve the quality of human life. She holds a Master’s degree in Creative Writing from the University of the Philippines, one of the top academic institutions in the world, and a Bachelor’s in Communication Arts from Miriam College. Her other feature articles can be read on and



Legs Day!

Man I Hate Legs Day.



Change privacy settings