FFMI calculator
How much muscle you carry for your height, in a number that can be compared between different people.
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This is worked out here, in your browser. Nothing you type — weight, height, anything — leaves your phone: this page sends no data anywhere.
How it is worked out
First fat-free mass: weight × (1 − fat ÷ 100). That is divided by height in metres squared, like BMI but without the fat. Then Kouri's correction so different heights can be compared: FFMI + 6.1 × (1.8 − height in metres). A trained man usually sits between 20 and 23; a trained woman between 16 and 19.
What it does not tell you
The result depends entirely on the body-fat number you feed it, and almost nobody knows that precisely: a bioimpedance scale can be several points off, and every point moves the FFMI. Use it to follow your own progress with the same measuring method, not to rule on whether someone is natural: that claim, so often made with a “limit of 25”, does not hold in a single number.
Where it comes from
Kouri et al. (1995)
“Fat-free mass index in users and nonusers of anabolic-androgenic steroids”, the source of the height correction.
VanItallie et al. (1990)
The fat-free mass index as a body composition measure.
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Free on Get NovastraThis is general training information, not medical or personalised nutrition advice. If you have a health condition, are pregnant or take medication, the person who decides is your doctor.