In wireless sensor networks, the coarse grained localization is a method to compute the position of randomly distributed sensor nodes. Without optimizations, it provides low precision which heavily depends on the transmission range of base stations. In this paper, we propose novel optimizations of Coarse Grained Localization with Centroid Determination (CGLCD) to determine the position of nodes more precisely. Our focus is to compute an optimal transmission range of all base stations and to reduce the total energy consumption. We present an analytic proof of a simple equation to determine the optimal transmission range in grid-aligned finite wireless sensor networks. Using this optimal transmission range, we reduced the positioning error about 80%. Thereby, nodes as well as base stations require lowest energy.