In this paper we use a micro-magnetic model to preview the switching behavior of very small plates deposited on a nonmagnetic substrate. These plates present a rectangular shape and sufficient small dimensions to expect a regular pattern of the magnetization. The micro-magnetic model is based on the calculation of the energy for a given external applied magnetic field. To calculate the different components of the energy, the crystal volume was subdivided into a number of small finite cubic elements. The magnetization is assumed as a constant vector inside each volume element, with equal magnitude, but different direction, in all elements.