This paper summarises a reverse method of transformer design where the construction details of the transformer are directly specified and are used to determine the device performance and ratings. Two magnetic models are presented for the inductive-reactance components of the Steinmetz ‘exact’ transformer equivalent circuit. The first model, based on magnetic circuit theory, is frequently taught in undergraduate power system courses at universities. The second model is based on magneto-static finite element analysis. The reverse design method is used to design two sample high voltage transformers. The performance of the two magnetic models is compared to the measured performance of the as-built transformers. The magnetic model based on finite element analysis is shown to be more accurate than the model based on magnetic circuit theory, though at the expense of complexity of programming.