Calculates your FFMI, normalized to a height of 1.8 meters (about 5 feet, 10-7/8 inches), as per the original study by the Clinical Journal of Sport Medicine.
Existing online FFMI calculators are flawed. For instance, the calculator at Natural Physiques does the math wrong (thanks to commenter "Derek" for pointing this out). It also does various other undesirable things during calculation that would produce significantly imprecise results, regardless. Nevertheless, this calculator uses the (corrected) code from that one, as the work was already done, so they deserve credit for that.
However, the study itself seems confused about its own math. There are various printing mistakes, such as multiplying when they actually divide, and not using enough brackets to clarify the formulae. Moreover, the abstract uses 6.3 in the normalization step; the article uses 6.1. Typos have been corrected; as for the discrepancy, this calculator follows the body of the article, not the abstract.
(todo: needs to specify fat % formula, which included age in study data - no existing calculator takes this into account)
Defaults taken from the average of non-users of steroids in the study.
Note that the study was conducted on individuals with 18% or less body fat according to a specific method of measuring or estimating, which likely differs from yours.
Results will not be meaningful for individuals who are less lean according to that method.