A measure that quantifies the amount of rotatability in a given response-surface design is introduced in this article. The measure, which is expressible as a percentage, takes the value 100 if and only if the design is rotatable. One of the main advantages of this measure is that it can be used to “repair” a nonrotatable design by the addition of experimental runs that maximize the percent rotatability over a spherical region of interest. Four numerical examples are given to illustrate the applications of this measure.