Abstract The paper presents iron loss estimation in a three-phase induction motor by using different iron loss models for the posterior iron loss calculation. The iron losses were determined by using modeled properties of used electrical steel and calculated distribution of magnetic induction B (t ) in all parts of the motor by using 2D finite element software for a complete cycle of field variation. The comparison between estimated and measured core losses for a 4 kW induction motor at no-load in dependency on supply voltage is given.