This paper discusses different measurement methods to evaluate the efficiency of WBG-based power supply solutions, including electrical measurement methods and their verification with calorimetric methods, and compares the performance of Si-based and GaN-based chargers. The efficiency of chargers was measured at different load conditions, and it was observed that the maximum efficiency occurred generally at higher powers. GaN-based solutions outperformed Si-based chargers at higher power levels, leading to significant energy savings. The paper suggests that regulations for efficiency can be tighten and different voltage modes shall be included to ensure further energy savings. The benefits of using WBG devices are more evident in terms of power density, which could lead to their wider adoption in other power electronic applications.