Precious metals such as gold and silver are often sold by the troy ounce. Many people don’t realize that an ounce of gold (and other precious metals) is weighed in a different weighing system called “troy weights”. A troy ounce is more than the typical ounce found at the grocery store.
In many English speaking countries there are two systems for measuring weight.
One, for precious metals, called the troy ounce. The other is for Commodities such as sugar, grains, and the typical grocery items. It is called the avoirdupois ounce.
The US often use the avoirdupois ounce for everyday weighing. Every time you step on the scale at home, or weight food found in the grocery, you use the avoirdupois ounce weight system. There are 16 avoirdupois ounces in a pound.
1 avoirdupois ounce = 28.35 grams. 1 avoirdupois pound contains 16 (avoirdupois) ounces. This makes an Avoirdupois pound equal to about 453.6 grams, or the equivalent of 14.583 “troy ounces”.
The troy ounce is heavier than the typical grocery store (avoirdupois) ounce used in the USA. When you purchase a 1 ounce silver or gold coin, you are receiving a “troy” ounce or 31.1 grams which weighs 10% more than the avoirdupois ounce many are familiar with.
A troy ounce is equivalent to about 31.1 grams.