Eddy-current effects in thick steel plates are investigated with particular reference to saturation. TheB/Hcharacteristic is represented by the Frohlich equationB=H/(a + bH). The field equations are expressed in nondimensional form, and the losses are computed using a numerical finite-difference scheme. The information is presented in the form of a loss chart which embodies the effects of thickness, conductivity, frequency, shape of the saturation curve and magnetic-field strength. Information is also given in the paper about the penetration depth and power factor. The calculations are compared with measurements on steel blocks.