Abstract: In a method for the mathematical, digital measurement of the phase difference of two periodic or cyclic signals U and V of the same frequency by averaging from n elementary measurements Mi, a timing signal of a much higher frequency and asynchronous with signals U and V is counted between directly succeeding zero pasages of signals U and V in the same direction. An elementary calibration Ci is performed in each cycle of U, in which an elementary measurement Mi is performed by counting the timing signals during the complete cycle of U. An overall phase difference is determined, in that the mean value of all the elementary measurements Mi is divided by a mean value of all elementary calibrations Ci and is multiplied by the cycle.