A method for calibrating a diagnostic measuring device for biological signals, which can be represented as vectors, such as the representation of cardiac potentials in cardiography. The method determines a zero-point vector or reference point for the calibration of the measuring device as an average vector within a resting section having minimal change of the signal. A search range for such a resting section can be limited to a time frame within the entire measuring period and biologically justified, for example, by means of empirical data that indicate physiological resting phases and/or from the knowledge of the course of the physiological process to be examined.
