The new definitions of the SI base units (pdf, 1984КБ) have now come into effect! 20 May 2019

The changes were agreed by the CGPM in November 2018 with effect from May 20th 2019, a date chosen because it is World Metrology Day, the day when the Metre Convention was signed in 1875. Whilst the future impact of the changes will be far reaching, great attention has been paid to ensure that these definitions are consistent with those in place at the time the change was implemented.

BIPM The International Bureau of Weights and Measures (French: Bureau international des poids et mesures)

World Metrology Day is an annual event during which more than 80 countries celebrate the impact of measurement on our daily lives. This date was chosen in recognition of the signing of the Metre Convention on 20 May 1875, the beginning of formal international collaboration in metrology.

Poster from VNIIM (pdf, 8417КБ)