In this article, a system is described for the analysis of spreading resistance data which includes carrier spilling through the solution of Poisson’s equation. The Poisson equation solution requires boundary conditions for the charge density on the beveled surface, which was modeled by considering the presence of surface states with levels within the band gap. Considering surface states allows the deviation from ideality of both n- and p-type calibration curves to be accounted for consistently without empirical contact resistance or variable radius corrections. In addition, the effects of finite probe penetration and change in energy gap due to probe pressure were considered to account for the reduction in peak resistance near junctions observed experimentally as compared to theoretical calculations. The software (SERAPES) can be used both to calculate simulated resistance profiles from doping profiles for process model characterization, as well as to calculate doping profiles directly from spreading resistance measurements.