In the past few years, wireless sensor networks (WSNs) have been widely used in applications such as disaster management, combat field reconnaissance, border protection and security surveillance. The main concern for the operation of WSNs is the energy consumption. For most applications, it could be impossible or inconvenient to recharge the battery because nodes are deployed in a hostile or impractical environment. Among the components of a sensor node, the radio unit which provides connectivity to the rest of the network consumes much energy. One of the requirements for designing a WSN routing protocol is energy efficiency. Cluster-based routing protocols have better energy efficiency as compared to other approaches. However, the existing cluster-based routing protocols gave less emphasis on forming equal clusters which leads to unbalanced energy consumptionwithin and between the clusters. In this thesis, we have divided the sensing region of aWSN into equal size clusters to balance the energy consumption between clusters during intra-cluster communication. Moreover, multi-hop routing is employed as the energy consumption is equal to the square distance from sender to receiver; multi-hop routing consumes less energy than single-hop routing. The performance of the proposed equal size cluster-based routing is compared with low energy adaptive clustering hierarchy (LEACH), and hybrid, energy-efficient, distributed clustering (HEED), the well know cluster-based routing algorithmsfor WSNs. Simulation results showed that the proposed scheme extends the life time of WSNs by minimizing the energy consumption of sensor nodes and by balancing the energy consumption of sensor nodes.