A radiofrequency calibration system for a direct-drive radiofrequency power supply includes a reference box that includes a reference circuit for converting a non-reference input impedance to a reference output impedance. The reference box has an input connector electrically connected to a radiofrequency output coupling of the direct-drive radiofrequency power supply. A radiofrequency power meter has a radiofrequency power input electrically connected to an output connector of the reference box. The radiofrequency power meter has an input impedance and an output impedance that substantially match the reference output impedance of the reference box. A cable has a first end electrically connected to a radiofrequency power output of the radiofrequency power meter and a second end connected to a test load that has an impedance that substantially matches the reference output impedance of the reference box. A controller is connected in data communication with a data interface of the radiofrequency power meter.