Troy Ounces - The Measure of Precious Metals

What is a Troy Ounce?

When someone speaks of something weighing an ounce, the chances are that they are referring to an Avoirdupois Ounce, which is the seldom-used "official" name for the ordinary ounce. Bathroom scales, kitchen scales, produce scales, and other "ordinary" scales calibrated in ounces use the ordinary "Avoirdupois" ounces.

However gold, silver, platinum, and gunpowder are measured using a different system of weight - the Troy Ounce. The two ounces, Avoirdupois and Troy, are not the same. Knowing the difference can be very important: If you are buying or selling precious metals, including gold, silver, and platinum coins, you need to be sure which type of ounce you are getting - because a Troy ounce is more than 9.7% heavier than an Avoirdupois ounce!

An "ordinary" (Avoirdupois) Ounce is exactly 28.349523125 grams - or 437.5 grains.

A Troy Ounce is exactly 31.1034768 grams - or 480 grains.

The "price per ounce" of gold, silver, and platinum quoted in the precious metals and commodities markets is always for Troy ounces.

Troy Ounces are the measurement used worldwide for precious metals. This includes bullion weights; the commodity market's price-per-ounce of gold, silver, platinum (also the other rare "Platinum Group Metals" rhodium, ruthenium, osmium, palladium and iridium); the precious metal "spot price"; and graphs that track the price changes of precious metals over time.

Whether buying or selling precious metals, be sure that every part of the transaction uses the same ounce – the Troy ounce!