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Implementing the new kelvin 2

InK 2

The global measurement system, grounded in the international system of units (the SI), is the essential foundation for reliable measurement. Such a measurement system, transnational and truly global, is absolutely necessary for trade, manufacturing, sustaining and improving quality of life.

In 2018 the International Committee for Weights and Measures (the CIPM) aims to redefine the SI units in terms of fixed values of fundamental constants (for the kelvin this means in terms of the Boltzmann constant). This will make a logical, coherent and complete system of units for the foreseeable future. This momentous change needs to be supported with all the necessary research and documentation to ensure that a successful transition to the new SI unit system takes place.

For the kelvin this means that the required primary thermometry methods, and in particular results, will need to be in place to facilitate effective unit redefinition.  A soundly founded mise en pratique for the definition of the kelvin (MeP-K), grounded in robust primary thermometry methods (i.e. those that are thermodynamically based) and results, are essential for a successful redefinition.

The kelvin redefinition is a once in a lifetime opportunity to fundamentally change the principles and practice of thermometry. InK2 project aims to lead the world primary thermometry community in this endeavour with nearly all the world leading National Metrology Institutes (NMIs) and other institutes in the field being involved in this project. This global aspect is essential to gain worldwide acceptance of the results and thus ensure an effective redefinition on a global scale.


For more information on the redefinition of the kelvin,
please visit

Latest publishable summary (November 2018)

1st  Newsletter  (March 2017)

2nd Newsletter  (January 2018)

3rd  Newsletter  (October 2018)

4th Newsletter   (June 2019) 

Statement concerning the redefined kelvin (June 2019)


You can follow the progress of the project and participate in discussion related to the new definition of the kelvin and its future implementation in InK2 project page at ResearchGate: RG/InK2 


Last update 26.6.2019