The present study suggests a technique to estimate the burn rate of non-aluminized propellant compositions. A random packing algorithm is used to generate a three-dimensional propellant pack consisting of spherical Ammonium perchlorate (AP) particles and Hydroxyl-terminated poly butadiene (HTPB) binder. Intercept lengths of AP and HTPB were obtained by slicing the propellant pack and lines drawn on the sliced planes. The average intercept lengths were recorded and then used as thickness of AP and binder sandwich propellants. A discussion on the choice of parameters is made for both AP monopropellant flame and the diffusion flame. Comparison of burn rates of computational results is done with experimental studies reported in literature. A reasonable match has been obtained in these comparisons. Further, temperature sensitivity, which is an important factor, has been estimated and the values are closer to those reported from experimental studies than the values reported by earlier studies.