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Changes to SI become legal in UK

Today, 13 June 2020, changes to the International Systems of Units (SI) have become enshrined in law in the UK.

In a landmark decision, made at the 26th meeting of the General Conference on Weights and Measures, representatives of the signatories of the Metre Convention voted to revise the International System of Units. The SI covers units for all measurement, but at the heart of the SI is a set of seven units known as the base units.

The base units are now defined in terms of constants that describe the natural world, which are the most stable references available for us to use.

The Weights and Measures Act 1985 and the Units of Measurement Regulations 1986 have both been amended by the Government, and these changes come into force today. As the UK’s National Metrology Institute, NPL was invited to comment on the two draft statutory instruments, which amend UK legislation. Richard Brown, Head of Metrology at NPL, with responsibility for the UK’s standards of measurement, coordinated a response considering the views of several subject area experts at NPL.  

Richard Brown, Head of Metrology, NPL said: “The definitions of the base units are now formulated in a way that allows us to turn future advances in technology directly into improvements in the accuracy of measurements. The revised SI future-proofs our measurement system so that we are ready for all future technological and scientific and other innovations that we are yet to imagine. It is therefore sensible that such significant changes are reflected in this update to the UK’s weights and measures legislation so that the new definitions can be properly recognised in law.”

The International System of Units is necessary to ensure that our everyday measurements remain comparable and consistent worldwide. Standardising such measurements not only helps to keep them consistent and accurate, but also helps society have confidence in the information produced from measurement.   

Find out more about the SI units

13 Jun 2020