TGFC - Activities

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This page presents the main TGFC current and future activities 


The primary output of the Task Group on Fundamental Constants is the multivariate least-squares adjustment (LSA) of the values of the fundamental constants of nature. Currently the TGFC produces new adjustments on a four-yearly cycle. Each cycle includes all experimental data that are published or accepted by the Task Group by December 31 of that year. The most recent adjustment was completed in 2015 with data accepted up to 31 December 2014 and it is known as the 2014 LSA.

The values and uncertainties of the 2014 LSA of the fundamental constants may be found online here.

The next adjustment will be a special adjustment in 2017, with data accepted up to 1 July 2017.


Deliverables (for 2015 and 2016)

Articles in the CODATA Data Science Journal or other refereed Journals.

Detailed review articles in Reviews of Modern Physics and in Journal of Physical and Chemical Reference Data on the 2014 CODATA adjustment of the fundamental constants.

Reports, white papers, other publications, technical proposals etc.

Task Group members expect to be continually involved in a number of publications involving fundamental constants within their respective fields of research and the proposed changes to the SI. 

Data products, web resources, software tools etc.

Posting of 2014 CODATA recommended values of the fundamental physical constants on the Fundamental Constants Data Center (

Conferences, workshops, meetings and associated reports.

Task Group members expect to be involved in a number of conferences, publications, and presentations involving fundamental constants, the 2014 LSA, and the proposed changes to the SI.  Of note:

  • Summer 2015 – Task Group meeting at the BIPM in conjunction with the meeting of the CCU.  Discuss preliminary results of the 2014 LSA and it’s influence on the SI redefinition effort.
  • 10 – 15 July 2016 – Task Group meeting in conjunction with the 2016 Conference on Precision Electromagnetic Measurements, Ottawa, Canada.  Discuss publication of the 2014 LSA and new relevant data since.

Other products or accomplishments

The Fundamental Constants web site contains not just the CODATA recommended values of the fundamental physical constants but also an extensive bibliography, as well as auxiliary information concerning fundamental constants and the International System of units.

The recommendations of the Task Group to the Consultative Committee on Units (CCU) have contributed to its recommendation to the CIPM that is intended to change the nature of the International System of Units in a significant way.  This change will have the effect of making many of the fundamental constants significantly more accurate and in most cases energy conversion factors will become exact.  The Task Group will continue to liaise closely with the CCU concerning the proposed change in the SI.  Most importantly, the Task Group will closely monitor these developments and be prepared for both the recommendation of fixed values and the dissemination of a new adjustment immediately after any change in the SI.

In this period the Task Group is dedicated to its primary objective - to perform the 2014 Least Squares Adjustment of the values of the fundamental physical Constants.


Find out more

TGFC main page


Past Achievements