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Older values of the constants Archive of older articles and tables of values The 2018 set of values of the basic constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology (CODATA) are provided for historical reference below: 2018 values:      Table of Adopted values Table of Non-SI units Table of Conversion factors Table of X-ray values Table of all values (PDF) Table of all values (ASCII) Table of correlation coefficients (ASCII) Wall Chart Wallet Card Detailed description of the 2018 adjustment, including the covariance matrix of selected constants: E. Tiesinga, P. J. Mohr, D. B. Newell, and B. N. Taylor, J. Phys. Chem. Ref. Data 50, 033105 (2021) E. Tiesinga, P. J. Mohr, D. B. Newell, and B. N. Taylor, Rev. Mod. Phys. 93, 025010 (2021)    Return to Latest values of the constants.