Convert from ounce to pound [troy]

Unit Definition (ounce)
The ounce is a traditional unit of weight. The avoirdupois ounce, the unit commonly used in the United States, is 1/16 pound or about 28.3495 grams. The avoirdupois ounce also equals 175/192 = about 0.911 457 troy ounce or 437.5 grains. The word ounce is from the Latin uncia, meaning a 1/12 part, because the Roman pound was divided into 12 ounces. The word "inch," meaning 1/12 foot, has the same root.

Unit Definition (pound [troy])
The pound [troy] is a second traditional unit of mass or weight. The troy pound, named for the French market town of Troyes, was the unit used in England by apothecaries and jewelers. The troy pound is divided into 12 ounces like the Roman pound. One troy pound is 373.242 grams, or exactly 144/175 = 0.822 858 avoirdupois pounds (13.165 72 avoirdupois ounces). The troy and avoirdupois pounds are connected by the grain: there are 5760 grains in a troy pound and 7000 grains in an avoirdupois pound.