The stone or stone weight (abbreviation: st.)[1] is an English and imperial unit of mass equal to 14 pounds (approximately 6.35 kg).[nb 1] The stone continues in customary use in the United Kingdom and Ireland for body weight.

England and other Germanic-speaking countries of northern Europe formerly used various standardised "stones" for trade, with their values ranging from about 5 to 40 local pounds (roughly 3 to 15 kg) depending on the location and objects weighed. With the advent of metrication, Europe's various "stones" were superseded by or adapted to the kilogram from the mid-19th century on.

  1. "stone", Concise Oxford Dictionary, Oxford University Press, 1964.
  2. United States. National Bureau of Standards (1959). Research Highlights of the National Bureau of Standards. U.S. Department of Commerce, National Bureau of Standards, 13. 
  3. National Bureau of Standards, Appendix 8 .
  4. National Physical Laboratory, P. H. Bigg & al. Re-determination of the values of the imperial standard pound and of its parliamentary copies in terms of the international kilogramme during the years 1960 and 1961
  5. pound avoirdupois.
  6. Weights and Measures Act of 1963.
  1. Per the 1959 International Yard and Pound Agreement,[2][3][4][5] adopted by the United Kingdom in 1963.[6] Prior to that agreement, various minor differences existed between national standards and their conversions to the metric system.
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