Fractals are geometric objects used to describe irregular shapes that have a fractional dimension and commonly appear in nature. Although several proposals for the study of perfect fractals at the basic level are present in the literature, only few proposals for the study of real fractals exist, which does not seem reasonable considering the wealth of the theme and its potentiality as an interdisciplinary topic. In this text, we present a simple and easily assimilable procedure to calculate the fractal dimension of any two-dimensional object. It only demands a computer with the free software ImageJ installed. This procedure is easily understandable, considering the basic school curriculum, and easily usable in a variety of school settings.