Disclosed is a method and a system for the automated computation of a length or width dimension of a moving platform. The method includes sending radio waves toward the platform along a predetermined transmission axis and acquiring at least one digital power profile signal representative of a received reflected signal power as a function of a radial distance along the transmission axis relative to a reference point. This method next includes applying a filtering operator on the acquired digital power profile signal, making it possible to obtain a filtered digital signal, determining, by computation, a first radial distance corresponding to a first variation peak of the filtered digital signal and a second radial distance corresponding to a second variation peak of the filtered digital signal, and the computing a radial dimension of the platform as a function of the first and second radial distances.