What is a Troy Ounce? Troy Ounce vs Standard Ounce

What is a troy ounce? Why is gold and silver measured in troy ounces? Are they different from a standard or avoirdupois ounce?

You’ll be an expert on the weights of precious metals by the end of this article.

What is a Troy Ounce?

A troy ounce is a unit of measure used for precious metals like gold, silver, and platinum. Interestingly, it is not part of the metric system or the imperial system still used in the USA. Instead, it has a unique historical origin. The troy ounce dates back to the 16th century French town of Troyes, a significant trade hub where it was standardised as 480 grains of barley

How Many Grams in a Troy Ounce?

There are 31.1034768 grams in a troy ounce, which also converts to 480 grains, or 0.0311034768 kilograms.This measurement differs from the standard ounce, which is only 28.349 grams.

When converting larger weights, it’s essential to note that one kilogram is approximately 32.15 troy ounces. 

Due to the close numerical values (31.10 and 32.15), there is a risk of confusion, which can lead to errors in conversion. Always ensure you are using the correct conversion factor to avoid mistakes.

What is the Abbreviation for a Troy Ounce?

The abbreviation for a troy ounce is ‘oz t‘ or ‘t oz’ in the gold and silver community, it’s such a common and accepted measure that you’ll often see it simply abbreviated as ‘oz.’

So when you see ‘oz’ for precious metals like gold, silver, or platinum, it usually means troy ounces (oz t). The standard ounce (AVDP ounce) is used for other items. Since they are both abbreviated as ‘oz,’ what makes them different from one another? Let’s take a look!”

Troy Ounce vs Standard Ounce (Avoirdupois Ounce)

A troy ounce, commonly used in the precious metals market, weighs approximately 31.103 grams, making it about 10% heavier than the standard avoirdupois ounce, which is 28.349 grams. 

To put it simply, one troy ounce is roughly 1.097 standard ounces. Conversely, one standard ounce converts to about 0.911 troy ounces.

Troy Pound vs Standard Pound (Avoirdupois Pound)

Another interesting fact is that while a troy ounce is heavier than a standard ounce, the troy pound is lighter than the standard pound. This is because a troy pound consists of only 12 troy ounces which converts to approximately 373.242 grams, whereas a standard pound contains 16 ounces which converts to approximately 453.592 grams. 

However, the troy pound is not used in the modern precious metals industry; only grams, troy ounces, and kilograms are standard units of measurement for these materials.

Troy Ounce Conversion

With many measuring units to convert to depending on the country that you are living in, understanding and remembering troy ounce conversions can become a challenge. 

To help you understand, we have put together a table with conversion of troy ounces to most widely used measuring units around the world: 

Why is it a Troy Ounce? History of the Troy Ounce

So why do we use troy ounces?

Despite the horse in our featured image on this page, a troy ounce has nothing to do with the ancient city of troy.

Troy ounces have been used in England since about 1400, and the English troy ounce was officially adopted for coinage in 1527. The troy ounce in use today is essentially the same as the British Imperial troy ounce (1824–1971), adopted as an official weight standard for United States coinage by Act of Congress on May 19, 1828¹. 

Some historians believe the troy ounce obtained its origins from Roman times. Romans standardized their monetary system using bronze bars that could be broken down into 12 pieces called “uncia” or ounce, with each piece weighing around 31.1 grams.

As Europe’s economic importance grew from the 10th century onward, merchants came to bustling trade market of Troyes in France from all over the world to buy and sell goods. 

It was therefore necessary to develop a new standardised monetary weight system to make doing business and transactions much easier.

Therefore, while the exact origins of the troy weight system remain uncertain, many historians believe that in order to ensure that trade was fair and efficient, there has been the standardisation and the widespread adoption of the troy ounce. 

Which is why the term “troy ounce” is believed to have originated from the French city of Troyes, and why precious metals like gold, silver, and platinum use troy ounces for the unit of measure.

Does the Troy Ounce Change the Precious Metals Price?

Someone new to the world of precious metals may wonder whether the troy ounce somehow changes the price you see quoted for precious metals.

However the price in troy ounces is what all other weights of gold and silver are based upon. So if you see prices for grams or kilograms of gold or silver, these are simply conversions based upon the current per troy ounce prices.

How Are Precious Metals Measured in Different Countries?

Even though precious metals such as gold, silver and platinum are usually measured in troy ounces (and grams), they are still measured differently in various countries. Here are some of the systems used around the world:

• North America: In North America, gold is measured in pennyweights. One pennyweight is equal to 0.0499 troy ounces or 1.55517 grams. 

• China and Hong Kong: In these regions, the Tael (also called Tahil) is used. The weight of a Tael varies:
  • In China, one Tael is 50 grams or 1.608 Troy Ounces 
  • In Japan, it is 37.5 grams or 1.206 Troy Ounces
  • Thailand: Thailand uses the Baht to measure gold. One Baht is equal to 15.244 grams or 0.4901 Troy Ounces.

• South Asia: Countries like Pakistan, India, and Nepal use the Tola. One Tola weighs about 11.66 grams or 0.375 of a troy ounces.

• Traditional Units: Historically, grains of wheat were used to measure weight. A grain is the smallest unit of weight in the troy and avoirdupois systems. Jewelers used Jewellers Grains before carats. One Jewellers Grain is a quarter of a carat.

Buying and Selling Precious Metals in Troy Ounces

Troy ounces are the standard way to measure gold and silver around the world. So, if you’re buying gold or silver in troy ounces, you’re on the right track.

All gold and silver coins from different countries are always made in troy ounce sizes. At Gold Survival Guide, all our gold and silver products, whether they are coins or bars, are priced in troy ounces. Even though silver is often priced in kilograms, this kilogram price is just a conversion from the troy ounce price.

Next you might also want to see: What Does Gold Spot Price (Or Silver Spot Price) Mean?

Editors Note: This article was originally published 8 May 2018. Last updated 8 July 2024.