Copper losses in magnetic coils depend on several geometrical parameters, as well as on frequency, in a way that makes their analytical modeling a quite difficult task. In this paper, we describe how we use a finite-element-analysis software to investigate a series of issues critical to the accurate determination of high-frequency copper losses in layered coils. Some of the issues we investigate are the impact of the edge effect and the winding pitch on the overall copper losses. We examine the effective resistance of windings with a hexagonal conductor arrangement and the validity range of the classic models for copper losses in windings with round solid wire. The results of this work help us to fully understand the real impact of two-dimensional effects in layered windings of real rather than ideal magnetics. They constitute a tool for the accurate calculation of losses, which is necessary for an optimized magnetic component design in power electronics applications.