Troy Ounce
Also: Troy Ounce, oz t, Ounce, ozt
The standard weight unit used worldwide in precious metals trading: one troy ounce equals exactly 31.1034768 grams of pure precious metal.
The troy ounce (abbreviated oz t or ozt) is the internationally recognised unit of measurement in which gold, silver, platinum and palladium are traded. One troy ounce equals exactly 31.1034768 grams. Importantly, the troy ounce always refers to the quantity of pure precious metal, not to the gross weight of a piece of jewellery or a coin.
A Troy Ounce Is Not the Same as an Ounce
In everyday life we encounter the avoirdupois ounce of around 28.35 grams – for example in food weights. The troy ounce used in the precious metals market is heavier and dates back to the medieval weight system of the French town of Troyes. Anyone comparing prices should therefore look carefully: in bullion trading a "price per ounce" almost always means the troy ounce of 31.1035 grams.
Why the Troy Ounce Matters So Much for the Price
The current gold price and the silver price are quoted on the world markets in US dollars per troy ounce. To arrive at the value of a specific bar or coin from there, you convert to grams:
- 1 troy ounce = 31.1034768 g
- 1 gram = 0.0321507 troy ounces
- 1 kilogram = 32.1507 troy ounces
A classic 100-gram gold bar therefore contains around 3.215 troy ounces of fine gold. You can determine the exact value in pounds most quickly with the Gold Calculator or – for any unit – with the Unit Converter.
The Troy Ounce in Bullion Coins
Many well-known bullion coins such as the Krugerrand, the Maple Leaf or the Vienna Philharmonic contain exactly one troy ounce of fine gold. For coins with a copper alloy (such as the Krugerrand) the total weight is higher than 31.1 grams because the added metal is included – but the fine gold content remains exactly one ounce. Alongside the full ounce, fractional sizes are also common: 1/2 oz, 1/4 oz, 1/10 oz and sometimes 1/20 oz.
In Brief
The troy ounce is the pivot of every price quotation in the precious metals market. Anyone who understands it can effortlessly convert world market prices, bar weights and coin denominations into one another – and can immediately tell whether an offer is fairly priced.