Lean Body Mass Calculator
Your FFMI Results:
|Fat Free Mass|
FFMI by Percentile
What is fat free mass index?
FFMI or fat free mass index essentially tells us how much lean mass we have based on weight, height, and current body fat levels. Fat free mass includes not only muscle, but bones, internal organs, and water content are also included.
FFMI vs BMI or body mass index
FFMI is similar to BMI or body mass index but it’s typically more accurate for determining actual body composition. BMI calculations only take into account age, weight, and height.
Well, this isn’t enough information to most optimally assess an individual’s body composition or health. BMI considers only the body weight in relation to height essentially. But the problem with this method is that two different people can have the same BMI even though one person may have more body fat than the other.
Therefore, those two individuals are grouped into the same category for health and this is very misleading. And typically, BMI results are categorized as the following based on the score…
- normal or healthy weight
As a result, the FFMI calculator seeks to address this issue and is more ideal for people who weight train and have more muscle mass on average. But you do need to already know your body fat percentage. However, getting a completely accurate number is probably not possible for most people but it can get close depending on the methods used.
Related: Check out our body fat calculator
FFMI considers PEDs
Now, typically, the average FFMI for males is about 19-21. But what’s interesting about this calculator is that it also considers individuals who use performance-enhancing drugs or PEDs. And anything above 25, is generally considered to fall into this category.
Therefore, it can actually be a tool used to potentially indicate whether someone is using.
Although, this method of measurement isn’t always entirely accurate as there are some exceptions. Some people are extremely genetically gifted and can without a doubt achieve a score above 25 without the use of performance-enhancing drugs. However, it’s widely accepted to be an accurate assessment for the majority of cases.
A score of 22-24 is usually indicative of a very advanced exerciser with great body composition as a result of lots of training experience with a good diet.
Why do we need to know FFMI?
You don’t absolutely need to know your FFMI because the mirror is a good indicator of how much body fat to lean mass someone has. Although, someone less experienced with assessing their own body will likely benefit from a tool such as our FFMI calculator.
The FFMI calculator can help you to determine how much muscle and/or fat loss might be ideal based on your goals. It’s basically a way to calculate your body composition so that you can effectively make any adjustments to fit within a certain range of scores.
It’s also a great calculator for those interested in changing their body mass and who want a more accurate assessment of their body composition compared to the basic BMI calculator.
Formulas to Calculate FFMI
- Total Body Fat = Weight in Kg * (body fat % / 100)
- Lean Weight = Weight in Kg * (1 – (body fat % / 100)
- FFMI = (Lean Weight in Kg / 2.2)/ ((Feet * 12.0 + Inches) * 0.0254)2
- Adjusted FFMI = FFMI + ( 6.3 * (1.8 – (Feet * 12.0 + Inches) * 0.0254))
What is the Fat Free Mass Index (FFMI)?
What are the standard FFMI levels for men and women? See the tables below.
Note: Your calculated score should be plugged into the following charts based on your gender.
FFMI Ranges for Men
|Description||FFMI Range||Body fat percent|
|Typical average guy||18-20||20-27|
|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|
|Typical average woman||14-17||22-35|
|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?
It’s well-known that men typically have more muscle and bone mass as well as less body fat than women on average (or ratio of body fat to lean mass). That’s not to say there aren’t exceptions but biologically, hormones and other factors are where the differences lie. Men have more testosterone and androgenic hormones that are conducive to leaner body composition by default.
Whereas women need more body fat for their hormone function (e.g. menstrual cycle) and genetically, they need more fat for the process of childbirth. Subsequently, women typically carry body fat differently compared to men (e.g. women typically carry more fat around the hips and thighs and men around the midsection).
But women also tend to carry healthier fat tissue than men which may also play a role in limiting the cardiometabolic risk factors for women compared to men. Women also tend to utilize fat better during exercise for what it’s worth. (1, 2)
Few would disagree though, that using performance-enhancing drugs can close the gap between the two genders when it comes to body fat to lean mass ratio.
What are the dangers of having too much, or too little body fat?
Body fat is good to have and is essential for sustaining basic life (e.g. energy, hormones, protecting organs, nerve health, etc). But too much and you run the risk of developing diabetes, heart issues and even cancer. On the other hand, too little fat and you compromise normal, healthy bodily function.
These two extremes are seen in very obese people and at the other end, very lean athletes (e.g. bodybuilders) who can get dangerously low. For example, a typically healthy body fat range for men is 14-24%, while it’s ideally 21-31% for women according to the American Council on Exercise (ACE). (3)
Subcutaneous fat is the more common fat, typically measured with a caliper or other method to determine body fat levels. It’s located under the skin. This fat should exist in healthy amounts and the FFMI calculator is a great way to know how much overall fat your body is carrying.
Visceral fat, on the other hand, is stored in the belly and at a deeper level to surround the organs. Therefore, high amounts of this fat is very dangerous and correlated with an increased chance for disease. (4)
Using the FFMI calculator is a great method in helping to reduce overall body fat levels since body fat is measured. Although, it’s typically quite obvious when someone is carrying too much body fat around the midsection and other areas as well.
So, following an exercise and diet regime conducive to good health and ideal body composition is always highly recommended.
How do I interpret the results?
After you type in the required information, you’ll see an estimate of your FFMI in pounds, amount of body fat in pounds, your FFMI score (table provided above), and your normalized FFMI score.
It’s pretty straightforward as you can see. Just plug your FFMI score into the ranges in the charts provided for both men and women. Don’t get discouraged if your score doesn’t land you in the perfect spot. It doesn’t necessarily mean you’re doing something wrong.
However, you can use the numbers to get to where you want to be. Just do it in a healthy way.
Frequently Asked Questions (FAQs)
What is the purpose of a FFMI calculator?
The FFMI or fat free mass calculator is a great tool for getting a relatively accurate measurement of an individual’s body fat to lean body mass ratio.
Therefore, it can help to determine an ideal range (based on your score) for body composition
Do you need to know your body fat to use the FFMI calculator?
You do need to know your body fat percentage, to get the most accurate result possible. Although, this can be a challenge in itself depending on the method used.
Who is the FFMI calculator most useful for?
Anyone can use the FFMI calculator to determine an estimate of their body composition. However, it’s a great tool for people who want to know how much muscle and lean mass they have compared to body fat.
It’s even useful to possibly determine if someone is using performance-enhancing drugs. Typically, a score of 25 or higher may indicate the use of PEDs because of a higher muscle mass score with low body fat.
What's the difference between FFMI and BMI?
Fat free mass index (FFMI) is a more accurate and detailed result when determining body composition as it includes body fat in the calculation.
Body mass index (BMI) is typically a basic calculation of weight relative to height without respect to body composition.
How to improve FFMI or fat free mass index?
Anyone can improve their FFMI by following an effective exercise/resistance training and diet regime. You don’t have to be perfect but making these changes will improve your level of muscle while keeping the fat low or even losing it.
There are safe ranges for FFMI though, which you can check out in the charts we’ve provided.
Using the FFMI calculator is simple. Not to mention, it helps to know your score which can subsequently allow you to better aim for a certain goal. It can help determine whether someone needs to shed a little more fat or gain more muscle mass with a relatively close estimate.
Also try our other calculators:
- Creatine Calculator
- LBM Calculator
- TDEE Calculator
- Carb Cycling Calculator
- Intermittent Fasting Calculator
- Macro Calculator
- Wilks Calculator
- Body Fat Calculator
- EER Calculator
- Weight Loss Percentage
- Bench Press Calculator
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