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CODATA Recommended Values of the Fundamental Physical Constants: 1998



Peter J. Mohr, Barry N. Taylor


This paper gives the 1998 self-consistent 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) for international use. Further, it describes in detail the adjustment of the values of the subset of constants on which the complete 1998 set of recommended values is based. The 1998 set replaces its immediate predecessor recommended by CODATA in 1986. The new adjustment, which takes into account all of the data available through 31 December 1998, is a significant advance over its 1986 counterpart. The standard uncertainties (i.e., estimated standard deviations) of the new recommended values are in most cases about 1/5 to 1/12 and in one case 1/160 times the standard uncertainties of the corresponding 1986 values, while the absolute values of the differences between the 1998 values and the corresponding 1986 values are almost all less than twice the standard uncertainties of the 1986 values. The new set of recommended values is available on the World Wide Web at
J. Phys. & Chem. Ref. Data (JPCRD) -
No. 6


CODATA, conversion factors, data analysis, electrical units, fundamental constants, Josephson effect, least-squares adjustment, quantum Hall effect


Mohr, P. and Taylor, B. (2000), CODATA Recommended Values of the Fundamental Physical Constants: 1998, J. Phys. & Chem. Ref. Data (JPCRD), National Institute of Standards and Technology, Gaithersburg, MD (Accessed June 21, 2024)


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Created November 1, 2000, Updated November 14, 2018