With an expansion in road networks, rigid retaining wall has become an inevitable geotechnical infrastructure. Determination of lateral earth pressure under various conditions is necessary for the design of a rigid retaining wall. In this study, a computer program was developed in C++ platform performing repetitive calculations for determining the base width required for a wall height, satisfying the required stability criteria (factor of safety). The consideration of earth pressure theories and its impact on the design and cost of gravity and cantilever retaining wall was explored with the help of the developed computer program. Considering both the earth pressure theories, it was found that gravity retaining wall is economical for retaining wall height (H) < 6 m and cantilever retaining wall is economically better for H > 6 m. Further, numerical modelling was performed in PLAXIS 2D, to study the influence of soil stiffness and wall movement on the development of lateral earth pressure on a cantilever retaining wall with base. The soil stiffness does not influence the lateral stress determination by numerical methods for at-rest condition of wall. With wall movement leading to the development of active condition, lateral earth pressure is higher for soil with lower stiffness value. With higher wall movement, the lateral earth pressure determined from numerical method approaches the active lateral earth pressure obtained from theoretical equations.