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Fundamental Physical Constants

Mission and objectives 

The purpose of the CODATA Task Group on Fundamental Physical Constants (TGFC) is to periodically provide the scientific and technological communities with a self-consistent set of internationally recommended values of the basic constants and conversion factors of physics and chemistry based on all relevant data available at a given point in time.


The TGFC’s commitment to producing a new least squares adjustment (LSA) of the fundamental constants on a four-year cycle incorporates all relevant data from diverse scientific interests and fields of research.   This function primarily provides the scientific and metrological communities the most consistent set of the values of the fundamental constants and conversion factors used in physics and chemistry.  Moreover, performing an analysis over a broad spectrum of experimental and theoretical information relevant to the constants has important value.  In general, such an analysis may uncover errors in theoretical calculations or experiments; it reevaluates uncertainties so that all are expressed in a consistent manner (i.e. standard uncertainties); it identifies inconsistencies among results and weaknesses in certain areas of research; it stimulates new experimental and theoretical work due to inconsistencies; and it summarizes a large amount of rather diverse information in one place.  These values contribute to the high profile of the TGFC’s LSA and the TGFC’s continued reputation as the authoritative source for the best determination of the fundamental constants.  The review articles of each LSA are very highly cited and contribute significantly to CODATA’s international reputation.

Task Group Websites


The next regular CODATA-TGFC four-year cycle adjustment of the fundamental constants will be the 2022 adjustment with a closing date of 31 December, 2022 for input data to be available for consideration.  Relevant data are presently being collected and reviewed for possible impact on the determination of the values of the fundamental constants. The results of the 2022 CODATA-TGFC adjustment will be made available later in 2023 with the accepted input data and analysis published in a review article.

Planned (and later on actual) activities and outputs for 2021-2023 (i.e. specific listing of outputs: reports, presentations, papers, events, etc.)

  • The 2021 TGFC meeting was hosted by the BIPM virtually 14-15 September 2021 in conjunction with the 25th meeting of the CCU.  Topics of discussion centered on new relevant input data, input data discrepancies that may lead to better understanding of fundamental theories, and preparations for the 2022 CODATA adjustment of the fundamental constants.  The 2020 TGFC meeting minutes were accepted and are posted on the BIPM website:
  • The International Committee for Weights and Measures (CIPM) has agreed on a Memorandum of Understanding (MoU) between the BIPM and CODATA. It was signed by Dr Martin Milton, Director of the BIPM and by Dr Simon Hodson, Executive Director of CODATA on 11 October 2021:
  • The next CODATA-TGFC meeting will be held in September 2022 with the precise dates to be decided early 2022. A hybrid meeting is presently planned and to be held at the BIPM, Paris with virtual attendance an option. The meeting will last up to three days with several scientific presentations on subjects of interest to the Task Group, including invited speakers on HD+ spectroscopy, electron-proton scattering, and measuring relative atomic masses.
  • The results of the 2022 CODATA-TGFC adjustment of the fundamental constants will be made available in 2023 with the accepted input data and analysis published in review articles.



  • Chair: Prof. Krzysztof Pachucki , Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, POLAND
  • Co-Chair: Dr Eite Tiesinga, NIST, Bldg. 220, Rm. B342, 100 Bureau Drive, Stop 8423, Gaithersburg, MD 20899, USA