This database gives values of the basic constants and conversion factors of physics and chemistry resulting from the 2002 least-squares adjustment of the fundamental physical constants as published by the CODATA Task Group on Fundamental Constants and recommended for international use by CODATA.
CODATA Internationally recommended 2010 values of the Fundamental Physical Constants
This site addresses three topics: fundamental physical constants, the International System of Units (SI), which is the modern metric system, and expressing the uncertainty of measurement results. Both essential information and background information are given for each topic.
re3data.org: The NIST Reference on Constants, Units, and Uncertainty;
editing status 2018-12-12;
re3data.org - Registry of Research Data Repositories. http://doi.org/10.17616/R3DD0N
last accessed: 2019-10-21