Performance of electromagnetic interference (EMI) filters in power-electronics applications is limited by the parasitic coupling between the components of the filters and the self-parasitic of each component. While these parasitic effects can be partially taken into account on the circuit level, it is difficult to estimate their values. In this article, a full-wave modeling methodology is proposed to predict the performance of a complete EMI filter up to 1 GHz. Following the proposed methodology, the mutual couplings among the EMI filter components are taken into account as well as the self-parasitics of each individual component. Experiments and simulations are carried out to validate the modeling methodology. A self-parasitic cancellation technique is also applied to demonstrate the benefits of three-dimensional modeling methodology in EMI filter design.