This paper presents an analysis of the factors affecting coverage and capacity estimation in cellular networks of third generation (3G) technology using wideband code division multiple access (WCDMA). Particularly in WCDMA systems, the main source of interference by coverage is the overlapping between cells, affecting the capacity of system. To analyze the factors affecting the capacity of a WCDMA network, we use the radio-planning tool Atoll™ where we simulate and describe two scenarios for the city of Managua. The first scenario shows the WCDMA network on the spread between cells that produce the effect known as excessive overlapping. The second scenario shows the optimized network, reducing the spread obtaining the optimal overlapping between cells, improving signal quality levels defined by signal to interference ratio Ec/Io. The throughput performance of the network is improved in 13.28% of the areas with speeds above two Mbps. From these results, we conclude that it is important to consider during the planning process or optimization of WCDMA networks the factors above mentioned that affect the performance and quality of service.