Improved magnetic component models, circuit simulation systems and methods are presented for simulating operation of a modeled magnetic circuit component in which user input defines magnetically susceptible core geometry of the modeled magnetic circuit component, a core model simulates operation of the magnetically susceptible core at least partially according to the geometry of the magnetically susceptible core, and one or more coil models simulate operation of coils wound around the magnetically susceptible core to provide a scalable model with geometry adjustable permeability for fluxgate magnetic sensors, transformers, inductors or other modeled components.