Precision meters of electromagnetic quantities are intended for high-precision measurements in all fields of science and technology. The research is devoted to the development of the method of calibrating meters to ensure the reliability of measurement results, and to achieve their required accuracy and metrological traceability. In the work, on the examples of calibration of LCR meters, meters of the phase shift angle between two harmonic voltages, analyzers of the pass power of high-frequency signals in coaxial paths, the general principles and basic provisions of the method of the precision electromagnetic quantity meters calibration in the full range of values of the measured quantities and in the full frequency range are disclosed. Schemes of measurements during calibration are presented, the content of model equations is disclosed in detail, the principles of formation and evaluation of budget components of measurement uncertainty during calibration are described. The method describes how to present calibration results in the form of a calibration diagram, as well as in the form of polynomial equations that can be used to calculate the error and evaluate the measurement uncertainty at any point in the range of values of the measured quantity. The method should be recommended for use by national metrological institutes, scientific metrological centres, calibration and testing laboratories. The method can also be used when conducting international reconciliations of the reference measurement standards of national metrological institutes, as well as when conducting interlaboratory comparisons of measurement results. The results of research will contribute to increasing the electromagnetic quantities measurements accuracy in all fields of science and technology.