FFMI Calculator


Enter your height



Your result is classfied as

Normalized FFMI
Fat-free mass
Total body fat
An image illustrating the step-by-step process of using an FFMI calculator. The image shows a user entering their weight, height, body fat percentage, and gender into the calculator's input fields. The next step displays the user clicking on the 'Calculate' button and the calculator generating their FFMI score. This image visually guides the user on how to use the FFMI calculator tool, which calculates an individual's Fat-Free Mass Index based on their body composition.

Introduction to FFMI Calculator

Tracking fitness progress goes beyond the scale. Metrics like the Fat-Free Mass Index (FFMI) quantify muscle building and leanness. 

key takeaways:

  1. FFMI estimates muscular potential based on height/weight.
  2. Adjusted FFMI accounts for current body fat levels.
  3. Track scores monthly to assess training effectiveness.
  4. Genetics influence your maximum attainable FFMI.
  5. Accurately input body fat % for precise analysis.

Introduction to the FFMI

The fat-free mass index compares lean weight to height. It estimates muscle stats based on:

  • Height
  • Weight
  • Body fat %

The resulting score reveals total fat-free mass attainable naturally. An adjusted value also accounts for current fat.

Monitoring FFMI over time displays:

  • Muscular potential
  • Diet effectiveness
  • Training consistency

Read on to maximize the use of this calculator.

Step-by-Step Guide to Measuring FFMI

Using the FFMI calculator requires four quick steps:

  1. Select metric or imperial units
  2. Input height in cm/in
  3. Input weight in kg/lbs
  4. Input body fat %
  5. Calculate FFMI

For example, for someone who is:

  • 6 ft 0 inches
  • 190 lbs
  • 15% body fat

The calculator estimates:

  • FFMI: 21.6
  • Adjusted FFMI: 23.3
  • Fat-free mass: 161.5 lbs

With accurate body composition stats, you now have tangible markers for lifestyle improvement.

Compare Adjusted vs. Original FFMI

Two core index numbers appear - original and adjusted FFMI:

  • FFMI accounts for only height and total weight, while...
  • Adjusted FFMI factors current body fat percentage.

Let's break these down further.

The raw FFMI score establishes a muscular baseline. It represents lean mass attainable at minimum body fat levels.

However, the adjusted FFMI better reflects present condition since most carry excess fat. This custom metric continues increasing as body fat drops.

Monitor both metrics as you lean out and gain mass over months/years of consistent training.

Analyze Fat-Free Mass Value

In addition to the index scores, the calculator displays total body fat-free mass.

Think of fat-free or lean mass as all weight excluding body fat:

  • Muscle
  • Bone
  • Organs
  • Water

This lean weight amount illustrates dietary adherence effectiveness for building and maintaining metabolic tissue.

Maximizing fat-free mass while minimizing fat boosts health and metabolism simultaneously.

"When both fat-free mass rises AND fat lowers, you efficiently transform body composition."

What is Considered a Good FFMI Score?

The maximum muscle levels and FFMI scores differ substantially between genders:




Peak Lean Mass

~100-120 lbs

~150-200 lbs

Highest Attainable FFMI



However, most individuals, especially beginners, will measure far below their genetic potential.

Moreover, an FFMI score means little without the full context:

  • Training history
  • Body fat %
  • Goal physique

A figure competitor may purposely stay leaner year-round than a powerlifter, despite having a lower FFMI.

Tracking Your FFMI Over Time

While single measurements provide a useful snapshot, comparing monthly scores delivers key trend analysis.

For example, imagine bulking over 3 months:



Body Fat %



Fat-Free Mass

Jan 1

185 lbs




161 lbs

Feb 1

192 lbs




163 lbs

Mar 1

199 lbs




167 lbs

Though overall weight and fat increased, lean mass and adjusted FFMI show optimal muscular improvements from the surplus.

Conversely, dropping body fat too quickly often backfires long-term for retaining new muscle growth. Find sustainable losing rates.

"Avoid fixating solely on body weight or fat when goals center around muscle building."

Further Considerations Impacting FFMI

Despite providing an accurate analysis, the calculator carries a few limitations:

  • Assumes accurate body fat% input
  • Does not consider ethnicity
  • Ignores muscle insertions
  • Genetics affect outcomes

Getting an inaccurate reading from faulty body comp analysis would skew index scores. Those with more precise DXA scans have better results.

Moreover, mesomorphs often experience higher FFMI values due to favorable muscle building genetics. An ectomorph must train harder for comparable gains.

Be realistic setting expectations for peak muscular potential within genetic boundaries. Measure progress against your own scores rather than comparing to others’ online.

Take Action with Your Updated Metrics

Completing the quick FFMI analysis is the initial step. Now adjust training and nutrition programs accordingly:

  • Improve lifting volume/intensity if scores plateau
  • Lower body fat slowly to avoid lean mass losses
  • Set realistic target monthly FFMI based on starting stats
  • Ensure sufficient protein intake for new growth

The FFMI calculator simplifies the improvement process when you track progress month-to-month.


The fat-free mass index provides clarity into your body composition journey beyond just weight. Monitor adjusted FFMI and total lean mass to ensure training efficacy for building muscle and losing fat. Be consistent tracking progress monthly while progressing program intensity to maximize your genetic potential safely.