In this chapter we describe the GRBM on-ground calibrations, with major emphasis on those performed with the full (except for solar panels) integrated satellite. The calibrations results are the basis of the derivation of the efficiency as a function of energy and photon direction in order to allow for counts to flux deconvolution with the GRBM and AC ratemeters, and of the building of the 240 channels response matrices for LS1 and LS3 for time averaged spectral analysis. In the last section of the chapter we discuss the preliminary analysis of calibrations data.