This paper presents a developed method to calculate the parameters for thirty-three squirrel cage induction motors operating at three-phase ac voltage of 380 volts. These motors are the total product of an Egyptian factory holding a license from SIEMENS international company to fabricate all parts of these motors. The parameters of all mentioned motors are computed based on the proposed method. Then, the performance characteristics of these motors are investigated at full-load using the conventional equivalent circuit in order to validate the proposed method. The obtained curves achieve significant convergence with the full-load values provided by the data sheets of investigated motors. This confirms the validity of the proposed method.