'Troy'
a System of Weight

Understanding the differences between the
Troy & Avoirdupois systems of weight

The Troy and the Avoirdupois (pronounced: a-ver-du-pois) weight measurement systems, have many differences.

The Troy measurement system is used to weigh precious metals bullion, gemstones, and gunpowder.

The Avoirdupois measurement system is most commonly used in the United States, and it is used to weighing one's self or for weighing produce.

However, the majority of the world's population, outside of the United States, uses the Metric system of weight measurement.

The place where people often get confused between the Troy and Avoirdupois systems of weight is when it comes to understanding their conversions between ounces and pounds.

One Troy ounce (ozt.) = 31.10 grams
One Avoirdupois ounce (oz.) = 28.35 grams

The differences between the two shows that a Troy ounce (ozt) is heavier than a Avoirdupois ounce (oz).

However, their differences reverse when they are used to weigh something by the pound.

There are 12 Troy ounces in one Troy pound, and there are 16 ounces in one Avoirdupois pound.

Furthermore, even though there are more grams in one Troy ounce, one Troy pound is lighter than one Avoirdupois pound (lb.):

1-Troy pound - 12ozt. x 31.10grams = 372.20 grams
1-Avoirdupois pound (lb) - 16oz. x 28.35grams = 453.60grams

It can get confusing if you try to weigh bullion in the Avoirdupois weight system, and it's not recommended, especially because precious metals bullion is priced on the market in Troy ounces. (gold, silver, platinum, palladium)

There is one exception: Copper.

Copper is the only precious metal that isn't priced in Troy Ounces, instead it's priced by the Avoirdupois pound (lb.)

The conversion chart below can help you figure out the differences between the two systems of weight.

Copper per 100 pounds
Avoirdupois (lbs.)

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