Pound (mass)

For other uses, see Pound (disambiguation).
"lb." and "lbs." redirect here. For other uses, see LB and LBS.

pound
One-pound avoirdupois weight, from the Musée des Arts et Métiers
General information
Unit system
Unit ofmass
Symbollb
Conversions
1 lb in ...... is equal to ...
   SI units   0.45359237 kg
   Avoirdupois   16 ounces

The pound or pound-mass is a unit of mass used in both the British imperial and United States customary systems of measurement. Various definitions have been used; the most common today is the international avoirdupois pound, which is legally defined as exactly 0.45359237 kilograms, and which is divided into 16 avoirdupois ounces.[1] The international standard symbol for the avoirdupois pound is lb;[2] an alternative symbol (when there might otherwise be a risk of confusion with the pound-force) is lbm[3] (for most pound definitions), # (chiefly in the U.S.),[4] and ℔[5] or ″̶[6] (specifically for the apothecaries' pound).

The unit is descended from the Roman libra (hence the symbol lb, descended from the scribal abbreviation, ℔). The English word pound comes from the Roman libra pondo ('the weight measured in libra'), and is cognate with, among others, German Pfund, Dutch pond, and Swedish pund. These units are now designated as historical and are no longer in common usage, being replaced by the metric system.

Usage of the unqualified term pound reflects the historical conflation of mass and weight. This accounts for the modern distinguishing terms pound-mass and pound-force.

  1. ^ Cite error: The named reference NGS was invoked but never defined (see the help page).
  2. ^ IEEE Std 260.1-2004, IEEE Standard Letter Symbols for Units of Measurement (SI Units, Customary Inch-Pound Units, and Certain Other Units)
  3. ^ Fletcher, Leroy S.; Shoup, Terry E. (1978), Introduction to Engineering, Prentice-Hall, ISBN 978-0135018583, LCCN 77024142.: 257 
  4. ^ "pound sign". Oxford English Dictionary. Archived from the original on 3 April 2018.
  5. ^ "Letterlike Symbols | Range: 2100–214F" (PDF). The Unicode Standard, Version 15.0. Unicode Consortium. p. 2100/2123. Retrieved 28 April 2011. 2114 ℔ L B BAR SYMBOL
  6. ^ "The Dictionary of Medical and Surgical Knowledge". 1864. Retrieved 22 September 2016.