<p>In this paper we generate coverings (consisting of finite families of rhombi) of the graphs of fractal interpolation functions. In this way, we give an answer to the important problem concerning the spatial extent of such functions’ image, which appears in geometric aided design. As a by-product we obtain estimations for the range of these functions derived solely from interpolation data and scaling parameters. We should stress upon the fact that the existing papers dealing with this subject focus on restrictions imposed on parameters of the iterated function systems generating the fractal function based on a fixed range of it. Some concrete examples and graphical representations are provided.</p>