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
Troy weight g, 12 oz t), while an avoirdupois pound is approximately 21.53% heavier at 7 000 grains (≈ 453.59 g). One troy ounce (oz t) is equal to grams. Also equal to avoirdupois ounces, exactly , or about 10% larger. The pennyweight symbol is "dwt". There are 24 grains in 1 dwt, and 20 dwt in one troy ounce. Because there were 12 troy ounces in the old troy pound, there would have been 240 pennyweights to the pound—the basis of the fact that the old British pound sterling of currency contained 240 pence. (However, prior to 1526, English pound sterling