United States customary units ounces. The fluid ounce derives its name originally from being the volume of one ounce avoirdupois of water, but in the US it is defined as of a US gallon. Consequently, a fluid ounce of water weighs about 1.041 ounces avoirdupois. The saying "a pint's a pound the world around" refers to 16 US fluid ounces of water weighing approximately (about 4% more than) one pound avoirdupois. An imperial pint of water weighs a pound and a quarter (20 oz). There are varying standards for barrel for some specific commodities, including 31 gal for beer, 40 gal for whiskey or
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