A digital self-calibrating power factor controller for an AC induction motor. During start-up a first number corresponding to the actual phase angle between motor voltage and current is determined and compared with a second number corresponding to a desired delay in energizing the motor. The second number is varied until both numbers are approximately equal. A third number corresponding to a desired phase angle is determined and stored and the system switches from start-up to run. The first number corresponding to the actual phase angle is now compared with the third number corresponding to the desired phase angle. The second number corresponding to a desired delay is now varied with motor load so as to keep the actual phase angle equal to the desired phase angle.