The results of the supplementary comparison in calibration of mass and conventional mass SIM.M.M-S11 are reported. This comparison was organized by seven mass laboratories members of Inter-American Metrology System SIM and stainless steel standard weights with nominal values 2kg, 1kg, 200g, 50g, 1g and 200mg were chosen. These values link this comparison with the key comparisons CCM.M-K4 and CCM.M-K5. For the evaluation of the reference value and the associated uncertainty the method of least squares has been chosen, and the determination of the degrees of equivalence was calculated using the normalized deviation criteria. The results show a general consistency of the measurements in mass and conventional mass between the participant laboratories.