Tsunami hazard analysis in tsunami-prone areas is crucial for disaster preparedness and mitigation. Tsunami hazard can be assessed using either empirical relationships or numerical simulations, with the latter offering greater accuracy. Numerical tsunami simulations involve transforming the governing differential equations into algebraic equations through numerical methods, which are then solved computationally. As for tsunami waves, the horizontal length scale (wavelength) is much greater than the vertical length scale (water depth), the shallow water equations can efficiently and sufficiently accurately describe the propagation and inundation phases of a tsunami. The finite difference method is a common numerical technique used to solve shallow water equations. This method approximates derivatives by using difference equations on a grid. Achieving accurate numerical solutions requires bathymetric data with sufficient resolution, which is not always available. Additionally, decreasing the finite difference grid spacing improves accuracy but also increases computational demand. This raises key questions: Can the lack of bathymetric data with sufficient resolution be compensated by reducing the size of the finite difference grid spacing? To what extent do the resolution of bathymetric data and the size of finite difference grid spacing play a role in the accuracy of tsunami numerical modeling? This study is an attempt to thoroughly investigate the impact of bathymetric data resolution and finite difference grid spacing on the accuracy of tsunami height estimations, focusing on Chabahar Bay in the Makran subduction zone as a real-world case study.