Wind power continues to attract humanity as a key source of renewable energy, where wind turbines play a crucial role in delivering sustainable electricity. Within these systems, the gearbox is a central component responsible for transmitting mechanical energy from the rotor to the generator with optimal efficiency. This study investigates the impact of gear tooth profile modification, specifically the addendum modification coefficient, on the efficiency of a two-stage wind turbine gearbox. Using the Hohn method, the analysis evaluates how efficiency varies with different profile shift values across both stages of the gearbox under steady-state operating conditions. Two gear configurations are examined, with particular attention to mass reduction and compactness of design. Results show that a moderate positive shift (x = 0.17) yields the highest efficiency, reaching up to 96.88%, while deviations from this optimum lead to increased friction and reduced performance. Notably, reducing the module in the second stage enables a 40% reduction in mass while maintaining high efficiency. These findings highlight numerically the significance of tooth profile design in optimizing gearbox performance, reducing wear, and minimizing power losses. The study provides valuable insights for engineers aiming to design lighter, more efficient, and longer-lasting gearboxes for renewable energy applications.