This paper focuses on the study of the losses in conductors and magnetic cores of a large air gap transformer dedicated to contactless energy transfer. It is composed of two E -shaped cores and two windings. In order to estimate the losses, homogenization method and three-dimensional finite-element method (3D-FEM) have been used. Indeed, the equivalent complex properties of the windings composed of Litz wire, and magnetic core in ferrite have been calculated from homogenization method. Then, they have been implemented in 3D-FEM simulations to compute copper and iron losses with accuracy and by considering working condition of the magnetic component. Theoretical approach is validated by experimental results for a prototype of 1.6 kW-100 kHz.