The ring core inductors are widely used in EMI filters to reduce the conducted emissions induced by the power converters. However, the high frequency behavior of these inductors is modified by the apparition of the stray capacitances. These elements have more influence on the efficiency of the EMI filters. In this paper, three modeling methods based on the finite elements method are proposed to calculate the stray capacitance of the core ring inductor that will be integrate in EMI filter design tool. Also, a new measurement approach of the permittivity of magnetic materials was proposed. Finally, the EMI filter model include the high frequency stray capacitances is used to calculate the insertion loss of the EMI filter in a wide frequency bandwidth.