High-flux-density materials, such as iron-based amorphous metal and 6.5% silicon steel for gapped inductors, and powdered alloys for gapless inductors, are very competitive for high-power-density inductors. The high-flux-density materials lead to low weight/volume solutions for high-power dc-dc converters used in hybrid-electric and electric vehicles. In this paper, the analytical selection of the magnetic materials is investigated, and modified performance factors are introduced for convection- and conduction-cooled magnetic components. The practical effects of frequency, dc bias, flux-density derating, duty cycle, airgap fringing on the core loss, and thermal configuration based on lamination direction are investigated for iron-based amorphous metal, 6.5% silicon steel, and iron-based powdered alloy material. A 2.5-kW converter is built to verify the optimum material selection and thermal configuration. Analytical, simulation, and experimental results are presented.