Induction motors have very large application areas in industry and urban systems like water pumping and distribution systems, steel and paper industries and etc. Monitoring and controlling the motor operation, have important effect on the operating performance of the motor, driver selection and replacement strategy management of electrical machines. This study describes a sensor less method for monitoring and calculating efficiency of induction motors. Verification and comparing of two sensor less and conventional method have been derived in this study. The method verification was applied on two different three phase induction motors with rated powers of 3 kW and 5.5 kW. The proposed method can be used for optimal control of induction motors, efficiency monitoring and motor replacement strategy.