A smart current transformer for determining primary current or power consumption, by stepping down the primary current to a secondary current for subsequent measurement by a connected meter. The current transformer is provided with a connected non-volatile memory for storing calibration data (and optionally identification data) regarding that particular current transformer. The calibration data can include the gain error and/or phase delay for the current transformer, as determined from prior calibration testing of the current transformer. The calibration data may be communicated to or otherwise determined by the meter, and used to calibrate the measurement of the secondary current, in order to determine the primary current or power consumption. Also disclosed is a system and method utilizing such a smart current transformer.