FFMI Calculator

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Our FFMI calculator calculates the muscle mass index on the weight, body fat, and height of bodybuilders and fitness lovers. This is a tool for your health to measure body mass while considering muscle and fat mass. The calculation uses three factors, namely the height, weight, and body fat percentage.

To use this calculator, you need to measure your height, weight, and body fat percentage first. You can use our Body Fat Calculator to calculate the percentage of body fat. Enter the height, weight, and body fat percentage in the given input boxes. You can choose from several units (cm, m, feet, inches, etc.) to enter your measurements. After entering the values, click the “Calculate” button to see the results. This fat free mass index calculator will compute Fat free mass, Body fat, Normalized FFMI, and FFMI for the given values.

What is FFMI?

FFMI stands for fat free mass index, which is an alternative to the BMI that is the muscle mass of one person. The average male scored approximately 19, and without steroids or other prohibited materials, it is difficult to score above 25.

The Body Mass Index (BMI) is conceptually similar to the FFMI, but instead of measuring body mass by height, FFMI measures muscle mass in a person in relation to his/her height. The amount of lean muscle mass in the body is calculated using FFMI. FFMI can predict how many muscles a body can gain, according to researchers.

It is a valuable indicator for people who want to lose weight, particularly those involved in muscle development and body fat reduction. For serious bodybuilding enthusiasts, FFMI is especially useful.

The FFMI charts below show the standard FFMI scale for both men and women.

Men – FFMI Ranges

PortrayalFFMI RangeBody fat percentage
Slim guy17-1810-18
Usual average guy18-2020-27
Fat or chubby guy19-2125-40
Gym going or athlete20-2110-18
Gym lover22-236-12
Bodybuilders etc.24-258-20

Women - FFMI Ranges

PortrayalFFMI RangeBody fat percentage
Slim woman14-1520-25
Usual average woman14-1722-35
Fat or chubby woman15-1830-45
Gym going or athlete16-1718-25
Gym lover18-2015-22
Bodybuilders etc.19-2215-30


FFMI Formulas

We have stated the several formulas below, including Total body fat, Lean weight, FFMI, and Adjusted FFMI.

FFMI \(= \dfrac{\Big(\dfrac{\text{Lean Weight [kg]}} {2.2}\Big)}{((Feet \times 12.0 + Inches) \times 0.0254)^2}\)

Adjusted FFMI = \(\text{FFMI} + (6.3 \times (1.8 - (Feet \times 12.0 + Inches) \times 0.0254))\)

Total Body Fat \(= \text{Weight[kg]} \times \Big(\dfrac{\text{body fat} \%} {100}\Big)\)

Lean Weight \(= \text{Weight[kg]} \times \Big(1 - \dfrac{\text{body fat} \%}{100}\Big)\)
to Lean Body Mass Calculator to meaure your LBM.

How to calculate FFMI?

Our FFMI calculator uses mathematical formulas that are currently approved and calculate the fat-free mass, Body fat, Normalized FFMI, and FFMI. The Normalized FFMI is intended for the athletes who are taller in height. We have explained the manual calculations for each one of them below. We will assume the values for the calculations of all the terms stated above.

step 1:

Calculation of body fat can be calculated by using this formula and is measured in kg.

Body fat \(= \text{weight [kg]}) \times (\dfrac{\text{body fat} \%}{100})\)

\(= 70 kg \times \Big(\dfrac{24}{100}\Big)\)

\(= 16.8kg\)


step 2:

You can estimate fat free mass by using its formula, and it is also measured in kg.

Fat free mass \(= \text{weight [kg]} \times \Big(1 - \dfrac{\text{body fat} \%}{100}\Big)\)

\(= 70kg \times \Big(1 - \dfrac{24}{100}\Big)\) 

\(= 70 \times 0.76 = 53.2kg\)


step 3:

FFMI is measured in \(kg / m^2\). To calculate FFMI use the formula:

FFMI \(= \dfrac{\text{fat free mass [kg]}}{\text{height [m]}^2}\)

\(= \dfrac{53kg}{1.72^2}\)

\(= \dfrac{53.2}{2.9584} = 17.98 kg / m^2\)


step 4:

Use the below equation to calculate adjusted or Normalized FFMI. It’s unit is also kg / m². 

Normalized FFMI \(= \text{FFMI} [kg/m^2] + 6.1 \times (1.8 - \text{height [m]})\)

\(= 17.98 + 6.1 \times (1.8 - 1.72)\)

\(= 17.98 + 0.488 = 18.468kg / m^2\)

Importance of FFMI

For overall health, normal body composition is vital. There is a direct link between longer life without diseases and maintaining a balanced level of body fat. If fat levels of a body are maintained at a normal level, chances of diseases will reduce automatically. Conditions such as cardiovascular disease, type 2 diabetes, and high blood pressure are heavily associated with excessive fat, or anything that changes the body's normal composition. To calculate High Blood In this section, you will learn about the fat-free mass index, its importance for a strong and healthy physical condition, and how professionals are benefiting from it over the years.

The Fat free mass is a constituent of bones, internal organs, and water content in the body, as well as muscles and connective tissue. The fat mass (FM) on the other hand, takes adipose tissues into account and is opposite to the FFM.

There are two categories of fat mass.

Essential fat

Essential fats are those that are not produced by the body. Primary functions like blood clotting and brain development rely heavily on essential fat. Men require 2%-5% of essential fats, while women need 10% -13% to maintain a sound body.

Non-essential fat

Non-essential fats are not required by the body to perform primary functions. It protects the inner organs and the body as well.

Fundamentally, your body needs the right amount of fat to maintain it healthy. Athletes have low body fat that helps them achieve maximum results. When professional sportspeople train to achieve maximum fitness, they get lower body fats.

The following fat chart, according to different fitness levels, has been published by the American Council on Exercise (ACE).


GroupMen Body Fat %Women Body Fat %
Essential fat2 - 5%10 - 13%
Athletes6 - 13%14 - 20%
Fitness14 - 17%21 - 24%
Average18 - 24%25 - 31%
Obese25% and higher32% and higher

Difference between BMI and FFMI?

BMI is considered a good indicator of body mass for the general public. But it doesn't distinguish fat from muscle if you have more muscle than the average person. The weight of the whole body is only compared to height in BMI. You can use our BMI calculator to calculate the body mass index.

The BMI cannot provide information on fat-free mass or fat mass alone, according to the researchers. It means that the BMI score will be high for lean athletes.

The weight of two men could be 160 lbs each, with the same height, but if you compare their bodies, one person has no fat belly, while the other person has a clear appearance with a big belly in the middle. If you calculate their BMI, it will be 23.6 with a height of 5 feet 9 inches, which according to the National Health Institute (NIH), is healthy.

The numbers may be the same, but there is an impressive physical difference. Besides, it shows that achieving esthetic physic requires strength and muscle training to make your body well-shaped.

Here, BMI assumes that fat is the source to gain weight. It is a negative health indicator in this case. FFMI is, therefore, a better tool to measure lean and active people.

Why is FFMI better than BMI?

When someone gains weight and the fat tissue increases, the person is less healthy. If a fitness enthusiast or an athlete is gaining weight due to an increased muscle mass, that is a good indicator for him. Both situations are identical in view of BMI, and weight gain results in an increase in BMI index. The fat free mass index comes in handy and gives the solution in these situations.

FFMI is defined, so that fat gain and muscle gain are separated. When fat mass increases, the FFMI index decreases, and if muscle mass increases, FFMI also increases. The FFMI can properly estimate the condition of a person's body and health. The Body Mass Index (BMI) is an overall health estimate that works best for most people. Note that BMI is mostly useless for someone who trains daily. Fat-Free Mass Index is a much effective and reliable choice for this kind of person with more muscle mass than the usual people.

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