A simple method for estimating the costs of building and operating a cellular mobile network is proposed. Using the empirical data from a third generation mobile system (WCDMA), it is shown that the cost is driven by different factors depending on the characteristics of the base stations deployed. When the site density increased, the operational and transmission costs tend to dominate rather than the radio equipment and site costs. The results also show how, for different capacity requirements, the costs can be minimized by a proper selection of macro, micro and pico base stations. In many scenarios, the macro base stations yield the lowest cost, indicating that the coverage (cell range) is an important parameter when designing wireless systems.