The More-Electric Aircraft (MEA) concept has been introduced as part of the process of reducing the environmental impact of air travel. Incorporating more electrical systems including motor drives has become increasingly attractive researched. High power density across the complete system is a key factor in the realization of this technology. This paper considers a motor drive sizing procedure with a focus on optimizing the main weight contributors which are identified as the electrical machine, grid input filters and converter cooling system. A multi-level integrated optimization method is then proposed, followed by an example of its application incorporating the sizing procedure above. Comparison of results between single-level optimizations and multi-level optimizations are then presented. Finally, this paper presents the software validation of the sizing functions performed using different multi-physics software.