This project presents the development of a numerical code aimed to perform the grain burnback analysis and predict the performance of a solid rocket motor. The Level Set Method (LSM) has been applied to calculate the grain burnback evolution of 2D and 3D grain configurations introduced by the user as an input. In addition, in order to implement the 3D grain burnback analysis, an innovative approach called Quasi-3D has been implemented towards reducing the computational time. The Quasi-3D approach consists of modeling the 3D grain surface through few 2D reference cross-sections, which are propagated using the LSM in 2D. Then, the 3D surface is reconstructed by interpolating the grain shape between the reference cross-sections. With respect to the internal ballistics simulation, 0D-unsteady and 1D quasisteady models found from the literature have been used. This way, the Matlab® code developed studies three different cases: 2D grain burnback and 0D unsteady flow, Quasi-3D grain burnback and 0D unsteady flow and Quasi-3D grain burnback and 1D quasi-steady flow. The results from 2D and Quasi-3D grain burnback and 0D unsteady flow tools have been compared against three reference cases, obtaining a high level of matching. The 1D quasi-steady flow model results are qualitative.