We study the front shape of avalanches produced in a rotating two-dimensional drum partially filled with small glass beads. We focus our work on the study of the length and shape of granular fronts, in particular how they do scale in terms of the physical parameters involved. A single scaling law for the length is found. This scaling law is also relevant for the behavior of the full shape of the fronts. More than 300 different fronts shape, for different values of the parameters collapse into an universal curve.