Pound (mass) has been defined as exactly . In the United Kingdom, the use of the international pound was implemented in the Weights and Measures Act 1963. An avoirdupois pound is equal to 16 avoirdupois ounces and to exactly 7,000 grains. The conversion factor between the kilogram and the international pound was therefore chosen to be divisible by 7, and an (international) grain is thus equal to exactly . In the UK, the process of metrication and European units of measurement directives were expected to eliminate the use of the pound and ounce, but in 2007 the European Commission abandoned the requirement
Pound (mass) as a mass equal to to match the definition of the international pound agreed in 1959. A troy pound is equal to 12 troy ounces and to 5,760 grains, that is exactly grams. Troy weights were used in England by jewellers. Apothecaries also used the troy pound and ounce, but added the drachms and scruples unit in the Apothecaries' system of weights. Troy weight may take its name from the French market town of Troyes in France where English merchants traded at least as early as the early 9th century. The troy pound is no longer in general use or