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
Troy weight by the international yard and pound agreement of 1959 as . Therefore, the troy ounce is , compared with the avoirdupois ounce, which is 437.5 grains or approximately 28.35 grams. The troy ounce, then, is about 10% heavier (ratio 192/175) than the avoirdupois ounce. Although troy ounces are still used to weigh gold, silver, and gemstones, troy weight is no longer used in most other applications. One troy ounce of gold is denoted with the ISO 4217 currency code XAU, while one troy ounce of silver is denoted as XAG. Troy weight probably takes its name from the French market