Not only are there tools for it, it's such a common problem that there's a Wikipedia list of just the solvers that are notable enough to have dedicated articles

Not only are there tools for it, it's such a common problem that there's a Wikipedia list of just the solvers that are notable enough to have dedicated articles: https://en.wikipedia.org/wiki/Comparison_of_EM_simulation_software https://en.wikipedia.org/wiki/Comparison_of_EM_simulation_so... Be warned that the learning curve tends to be steep if you don't have the background down. It's far simpler in most cases to approximate your circuits and say "Good enough" unless you're venturing into pretty wild territory (antennas and high frequency), so most of the offerings tend to be either academic, military, or high end commercially focused.