Selecting an appropriate soil constitutive model and determining the corresponding model parameters for numerical analysis are considered most challenging in geotechnical engineering. While many empirical relationships have been proposed to derive soil parameters from in situ test results, there is no clear procedure on how to derive model parameters uniquely. In practice, available data during the early stages of projects is often limited to field test data. Consequently, different engineers provide different numerical solutions for the same problem. As a solution, the authors present a proof of concept for an automated parameter determination (APD) system, using concepts of graph theory to determine constitutive model parameters from in situ tests while keeping the system transparent (verifiable) and adaptable (extendable). The study aims to increase the confidence in parameter determination for numerical analysis by giving the user of the system, the geotechnical engineer, control over the system. Using a spreadsheet of parameters and equations as input, the system generates paths between the parameters and calculates the parameter values for coarsegrained soil, starting from CPT data. Further validation and tweaking of the system, as well as the extension to other types of soils, are part of ongoing research.