A calibration method for the scale factor of an axisymmetric vibratory gyroscope functioning by application of an amplitude control signal, of a precession control signal and of a quadrature control signal to a resonator so as to set it into vibration at its resonant frequency, characterized in that the method comprises the following: first pre-calibration steps consisting of: applying the amplitude control signal, precession control signal and the quadrature control signal to the resonator so as to set it into vibration at its resonant frequency, and also applying a modulated quadrature control signal having a constant modulation frequency above a passband of a quadrature control loop of the gyroscope; measuring a resulting initial modulated quadrature detection signal value and storing the initial measured modulated quadrature detection signal value in memory; and measuring an initial scale factor of the resonator and storing the initial scale factor in memory; second subsequent steps of: applying the modulated quadrature control signal; measuring a resulting current modulated quadrature detection signal value; and calculating a corrected scale factor according to a relationship of proportionality including the initial scale factor, the initial measured modulated quadrature detection signal value and the current measured modulated quadrature detection signal value, according to the formula: Corrected scale factor = Initial scale factor × Current measured quadrature detection signal value Initial measured quadrature detection signal value first pre-calibration steps consisting of: applying the amplitude control signal, precession control signal and the quadrature control signal to the resonator so as to set it into vibration at its resonant frequency, and also applying a modulated quadrature control signal having a constant modulation frequency above a passband of a quadrature control loop of the gyroscope; measuring a resulting initial modulated quadrature detection signal value and storing the initial measured modulated quadrature detection signal value in memory; and measuring an initial scale factor of the resonator and storing the initial scale factor in memory; second subsequent steps of: applying the modulated quadrature control signal; measuring a resulting current modulated quadrature detection signal value; and calculating a corrected scale factor according to a relationship of proportionality including the initial scale factor, the initial measured modulated quadrature detection signal value and the current measured modulated quadrature detection signal value, according to the formula: Corrected scale factor = Initial scale factor × Current measured quadrature detection signal value Initial measured quadrature detection signal value applying the modulated quadrature control signal; measuring a resulting current modulated quadrature detection signal value; and calculating a corrected scale factor according to a relationship of proportionality including the initial scale factor, the initial measured modulated quadrature detection signal value and the current measured modulated quadrature detection signal value, according to the formula: Corrected scale factor = Initial scale factor × Current measured quadrature detection signal value Initial measured quadrature detection signal value