per troy ounce
Cost per massexact by definition
Cost per troy ounce, exactly 31.1034768 grams. It is the pricing unit for gold, silver, platinum and palladium on every major exchange. The conversion is exact, the troy ounce being exactly defined as 1/12 of a troy pound of 373.2417216 grams.
Watch out: Bullion prices are quoted per troy ounce of pure metal. A coin or bar described as one ounce is usually one troy ounce of fine metal with alloy on top, so its gross weight can be higher without any extra metal value.
| 1 $/oz t | 32.150747 $/kg |
The troy system takes its name from the fair at Troyes in Champagne, and it survived the metrication of everything else because bullion contracts, assay conventions and centuries of price records are written in it. A troy pound is twelve troy ounces, not sixteen, so it is lighter than an avoirdupois pound even though its ounce is heavier.