In high frequency planar transformers and induc- tors, conventional wires have been replaced by printed circuit boards or laminated copper windings. This technology can outperform traditional wire-wound transformers in terms of cost, dimensions and performance. However, in order to obtain high efficiency and high power/size ratio, their design requires the knowledge of the internal temperature distribution. For such a reason, this paper proposes a two-dimensional numerical method for a combined computation of both the temperature distribution and the electromagnetic behaviour of planar transformers and inductors. After a detailed description of the proposed method- ology, this paper reports, compares and analyzes calculated and measured results demonstrating prediction capabilities of the proposed method.