This work presents some considerations about the computation of the relative variance for Interval Type-2 Fuzzy Sets. Based on experimental evidence, the computation of the relative variance of an interval Type-2 fuzzy set using the KM algorithm needs more computations than using the original KM algorithm in order to obtain their boundaries since the variance combined with the KM algorithm results in a nonlinear behavior. A modified KM algorithm for computing the relative variance of an interval type-2 fuzzy set is proposed and a comprehensive analysis of its behavior is provided through two examples.