This paper describes a method of calculating the iron losses from a few macroscopic experiments for non-oriented steel plate with sinusoidal and non-sinusoidal excitations, taking into account saturation and hysteresis. With macroscopic considerations, iron losses are calculated using the Poynting vector and Maxwell's relations, and can be separated into two components : hysteresis and eddy current losses. These losses are studied by means of a method combining the finite element technique for spatial problem and the finite difference technique for time discretisation, associated to the Preisach model for simulation of hysteresis. Computed and experimental results are presented for sinusoidal and non-sinusoidal flux.