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
Anglo-Saxon pound × 32 = 7680 wheat grain. The Tower wheat grain was defined as exactly of a troy grain. Expressed in modern English troy grains, the Tower pound was 7680 × = 5400 modern troy grains (350 g). The Tower pound was divided into 12 ounces, each ounce into 20 pennyweights, and each pennyweight into 24 barleycorns. There were thus 480 barleycorns to a Tower ounce, 5760 barleycorns to a Tower pound of 350 g. The Anglo-Saxon pound (Saxon pound, moneyers' pound or Tower pound) remained in use for silver and gold coinage in England after the adoption of the medieval