Redefinition of the kilogram and the impact on its future dissemination

In view of the proposed redefinition of the kilogram, in 2005, 2007 and 2010 the CCM adopted recommendations and conditions to be met before the redefinition is implemented. Some of these conditions concern the uncertainty by which the kilogram will be realized after the redefinition. This uncertainty has become a point of discussion in other committees, because the needs for this value were not sufficiently transparent. Here, examples of the realization of the new kilogram with different uncertainties, along with the experimental results available from the Avogadro and watt balance experiments, the uncertainties of mass determinations and their propagation with reasonable assumptions are presented, in order to compare possible realization uncertainties with the requirements in practice. It turned out that the CCM conditions are reasonable, if major changes in the dissemination chain of the kilogram are to be avoided.