16 CFR 500.19 - Conversion of SI metric quantities to inch/pound quantities and inch/pound quantities to SI metric quantities.
(a) For calculating the conversion of SI metric quantities to and from customary inch/pound quantities, the conversion chart published in the following handbook shall be employed: National Institute of Standards and Technology (NIST) Handbook 133, Checking the Net Contents of Packaged Goods, Appendix E - General Tables of Units of Measurements, 2015 Edition, adopted November 2014. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 1 CFR part 51. You may obtain a copy of NIST Handbook 133 at the National Institute of Standards and Technology's Web site, http://www.nist.gov/pml/wmd/pubs/hb133.cfm. You may inspect a copy at FTC Library, (202) 326-2395, Federal Trade Commission, Room H-630, 600 Pennsylvania Avenue NW., Washington, DC 20580, or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal-register/cfr/ibr-locations.html.
(b) The SI metric quantity declaration should be shown in three digits except where the quantity is below 100 grams, milliliters, centimeters, square centimeters or cubic centimeters, where it can be shown in two figures. In either case, any final zero appearing to the right of a decimal point need not be shown.