The optimum configuration of rotor-to-generator size for wind turbines is dependent upon the wind resource and is the configuration that produces the most electrical energy at a fixed capital cost. This optimization study held the combined cost of the rotor plus generator constant, but varied the respective sizes of the rotor and generator within this constraint. Total annual electrical energy was computed for each configuration at a series of wind resources each defined by a different Weibull probability distribution. In each case the configuration that produced the most electrical energy was determined to be the optimum. The fixed capital cost was also varied to see the effect on the optimum at each wind resource. It was found that the optimal rotor-to-generator size decreased as the average wind speed at a resource increased, and increased as Weibull shape parameter k increased. The optimal rotor-to-generator size decreased at a constant wind resource as the fixed capital cost increased. In each case there was a corresponding optimal capacity factor which never exceeded 0.5. Capacity factors above this optimum resulted in less electrical energy being produced for the same capital cost. The final product of the study is a series of graphs showing the optimum rotor size for a given generator size at a series of wind resources.