In this chapter, we employ full-wave simulation methods to calculate shielding effectiveness in various scenarios. The chapter begins with a comparison between a simulation model and an analytical solution for the shielding effectiveness of planar materials. In this comparison, we discuss in detail how the assumptions required for the analytical solution and the specific characteristics of simulation models must be understood to ensure a meaningful comparison. Following this, we present the first application example, where we simulate the shielding of magnetic fields emitted from a cable pair carrying a large current. After analyzing this cable in isolation, we extend the study to a realistic vehicle model, calculating the magnetic field and comparing the results against regulatory limits imposed for human safety. In the second application example, we examine the shielding effectiveness of a rack-mount enclosure and compare the results obtained from two different source configurations used in the computation.