Advances in GaN-HEMT devices have encouraged the development of power converters at megahertz-level. However, inductors for high-frequency power converters require innovative approaches to overcome challenging constraints in both power and frequency. In this context, this paper presents an extension of the Parseval's theorem for the inductor analysis based on the energy conservation principle in the time and the frequency domains. Our approach aims to provide insights about the inductor power losses using high-frequency parameters and the inductor current harmonics. The proposed approach disaggregates the power losses in the frequency-domain for the inductor power signals in the time-domain. Main findings from the presented methodology provide useful selection criteria for inductors in power converters given parameters of quality factor (Q) and Self Resonance Frequency (SRF). Simulation results show the impact of the inductor behavior on the switching losses. An experimental setup validates the proposed approach. A high-frequency boost converter is presented as a study case.