Troy ounce
A troy ounce is 31.1034768 grams, the unit in which gold, silver, platinum and palladium are quoted internationally. Explanation, conversion to grams and kilos, and the difference from the ordinary ounce.
A troy ounce is a unit of weight of exactly 31.1034768 grams, used for precious metals. Gold, silver, platinum and palladium are quoted internationally in dollars per troy ounce, and most bullion coins such as the Krugerrand and the Maple Leaf contain exactly one troy ounce of fine metal.
The troy ounce is heavier than the ordinary (avoirdupois) ounce of 28.35 grams used for weight in the US. The difference comes from the medieval weight system of the trading town of Troyes in France. A kilo is 32.15 troy ounces; a troy ounce is 1/12 of a troy pound.
Dealers in the Netherlands and Belgium usually quote in euro per gram or per kilo. Converting: price per gram × 31.1035 = price per ounce; price per gram × 1000 = price per kilo. The prices page shows all three side by side.
Frequently asked questions
How many grams is a troy ounce?
31.1034768 grams, in practice rounded to 31.10 or 31.1035 grams.
How many troy ounces is a kilo?
32.1507 troy ounces, so a kilo bar of gold holds a little over 32 ounces.
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