The multidimensional output-pressure behavior of non-Newtonian fluids in single-screw extrusion can only be determined by using numerical methods. We present two methods which employ mathematical models building on analytic equations developed using an evolutionary heuristic optimization algorithm. Both allow fast and stable calculation of the 2-dimensional throughput-pressure gradient relationship of single-screw extruders, rendering cost-intensive CFD simulations of the output-pressure behavior redundant. A performed error analysis showed that our methods yield good approximations of the numerically determined data.