Revising the SI - news, updates and events

Event | 26 September 2018

In the lead up to World Metrology Day 2019 the MSL team will be delivering and partnering on several events to help communicate the importance and impact of the SI revision - we hope you can join us!

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International System of Units Redefinition, 2019

The International System of Units, known as the SI, is the globally-agreed basis for expressing measurements at all levels of precision, and in all areas of science, technology, and human endeavour.

The SI is presently made up of seven base quantities that each correspond to a universally-recognised unit.

The SI will undergo a major revision in May 2019 that will be implemented by the international measurement community. This global change involves moving away from material artefacts (e.g. the kilogram prototype in Paris), and instead employing a set of seven defining constants, from which all units can be derived.

The Measurement Standards Laboratory is the primary agency responsible for implementing the new SI definitions into New Zealand. Adopting the definitions will allow NZ to remain consistent with international best practice and allow precision measurement to be available to everyone.

Four of the base units – the kilogram, ampere, kelvin, and mole – will be redefined based on fixed numerical values of the Planck constant (h), the elementary charge (e), the Boltzmann constant (k), and the Avogadro constant (NA), respectively. The three remaining base units – the second, metre and candela – are already defined by physical constants, so it will only be necessary to edit their present definitions.

Why do we need the SI?

  • For fair domestic and international trade, so when you buy or sell a quantity of something you and your customers know what you are getting without being cheated or surprised.
  • So that things made in different places, countries, or even factories across the street will fit and work together.
  • To provide a common basis to communicate measurements in science, engineering, health, safety and the public good.

Want to know more?

You can download a handy factsheet on the changes here [PDF, 373 KB] [PDF, 382 KB].

And read more about each of the measurement units here.

Or read our case study 'Quantum Balancing Act for the SI'


Coming Events

1 November 2018 - An event celebrating 150th Anniversary of NZ Standard Time

February - May 2019 - Regional Roadshows

MSL will be taking measurement to the regions with a series of events in our main centres (Auckland, Hamilton, Wellington, Christchurch and Dunedin) for measurement testing laboratories, industry and innovators.  We’ll share the latest information and impact the changes to the SI will have on businesses both here, and around the globe.

Events will be held in partnership with the Metrology Society of Australasia, and our Regional Business Partners.

More details and registration information will be available shortly.

20 May 2019 - World Metrology Day

World Metrology Day is an annual celebration to mark the signing of the Metre Convention on the 20th May 1875, which set the framework for global collaboration in the science of measurement. 

In May 2019, the historic change will take place, and we will finally see all the SI base units (International System of Units), such as the kilogram and the kelvin, referenced to a fundamental constant, as opposed to a physical artefact.

More details on how New Zealand will mark this milestone will be available shortly.