In 2018 the kg will be defined by Planck's constant,

Defining the kilogram in terms of fundamental physical constants will ensure its long-term stability, and hence its reliability, which is at present in doubt.

What impact does the redefinition have on the realization of the kilogram?

kilogram will be defined in terms of the Planck constant, guaranteeing long-term stability of the SI mass scale. The kilogram can then be realized by any suitable method, (for example the Kibble (watt) balance or the Avogadro (X-ray crystal density) method). Users will be able to obtain traceability to the SI from the same sources used at present (the BIPM, national metrology institutes and accredited laboratories). International comparisons will ensure their consistency.

The value of the Planck constant will be chosen to ensure that there will be no change in the SI kilogram at the time of redefinition. The uncertainties offered by NMIs to their calibration customers will also be broadly unaffected