The method of determining efficiency by segregating motor losses is the preferred method adopted by most efficiency regulation programs in the world, but because the standards adopted are different, there are some differences in the methodologies used to calculate these losses and consequently the motor's efficiency. There is a movement among standardization bodies to harmonize test methods in order to achieve equivalent results between the methods adopted by the standards. The aim of this article is to analyze and compare the latest editions of the NBR, IEC, IEEE and CSA standards for determining the efficiency of three-phase induction motors using the loss segregation method, in order to verify their equivalence and harmonization. To do this, the power supply requirements, instrumentation requirements and test procedures adopted are checked and compared. The test procedures used for loss separation in each standard were compared: method 2-1-1B of IEC 20034-2-1(FDIS 2022), method B of IEEE 112:2017, method 2 of NBR 17094-3:2018 and the single method of CSA C390:2016. Finally, the results of the efficiency determination obtained in tests carried out on 10 motors with power between 0.75 kW and 750 kW (0.75 kW, 3.0 kW, 7.5 kW, 15 kW, 30 kW, 75 kW, 150 kW, 300kW, 400kW and 750kW) according to the procedures and methodology of each standard analyzed, in order to verify the variation in the efficiency of these motors when subjected to the methodologies of the different standards, in order to show the existence of equivalence of the results between them.