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What Is a Troy Ounce?

There is a lengthy history of coins, precious metals, and monetary systems. Consequently, there have been numerous ways to weigh and measure coins. One of the oldest units of measurement is the troy ounce. And, it is still in use in some circles today.

What Is a Troy Ounce?

It is a medieval unit of measurement named after its origins: Troyes, France. People have long been using it to measure precious metals. The British Empire first adopted this practice in 1527. And, the U.S. has been using it since 1828.

What Is a Regular Ounce?

When people refer to an ounce, they often mean the avoirdupois ounce, which is 1/16 of a pound. Avoirdupois is the name of the system of weights used in the U.S. and some other English-speaking countries.

What’s the Size of a Troy Ounce vs. an Ounce?

  • A troy ounce is 31.1 grams
  • A regular ounce is 28.3 grams

History of the Troy Ounce

Although it got its name from Troyes, France, it is less clear where the unit of measurement originated. Many believe that the Romans used this measurement, as the Romans made great strides to standardize monetary systems. Among these systems, Romans used bronze bars made of 12 individual “unicas,” and each piece weighed around 31.1 grams, similar to it. Therefore, historians believe that merchants of Troyes modeled their monetary system using similar weights to the Romans.

Using This Measurement Today

In general, buyers and sellers use this in lieu of common ounces when it comes to buying and selling gold, silver, and other precious metals. So, it’s important to be familiar with this unit of measurement as some sellers will try to boost the apparent value of their products by listing them in ounces. For example, buyers could purchase 100 ounces of gold bullion and lose 10 percent of the value of their purchase, as it only weighs 90 troy ounces.

Gold Coins

Not all these coins weigh exactly one troy ounce or 31.1 grams. Two of the most popular gold coins in the industry are American gold eagles and South African gold krugerrands. These coins are 22k and are composed of gold and base metals for durability purposes. They contain exactly one troy ounce of fine gold. However, the additional base metals used in the production of these coins brings the total weight to 33.93 grams.

Troy ounces are one of several basic terms to be familiar with as a buyer or seller of precious metals or coins. For more information about the process or to learn more about our products, view our current inventory online or call 404-236-9744 to request an appointment with Atlanta Gold & Coin Buyers.

Tony Davis
Tony Davis
Tony Davis is the owner of Atlanta Gold & Coin Buyers, a full service Atlanta based coin and bullion dealer specializing in buying, selling and appraising coins and coin collections of all types and sizes. Tony frequently writes on various economic and numismatic related topics affecting the coin and bullion markets and has been published on some of the industry’s leading websites, including Coin Week, the American Numismatic Association, Coin Collector, Coinflation, and Coin Auctions Help, just to name a few. Visit Atlanta Gold & Coin’s website at to obtain additional information on the products, services and educational resources offered by his company. Tony can be reached at or at 404-236-9744
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