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
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