Atkinsons Bullion & Coins
Back to News

First-time precious metals investors are often surprised to find that a unique unit of measurement is used to weigh gold and silver: the Troy Ounce. The troy system is a different measurement system to the standard ounce (known as the avoirdupois ounce), so why do we use this system and where does it come from?

What is a Troy Ounce?

A troy ounce is a little heavier than an avoirdupois ounce. One avoirdupois ounce is 28.35 grams, and a troy ounce is 31.10 grams. With a difference of 2.754 grams, a troy ounce is around 10% heavier than an avoirdupois ounce.

The Origin of the Troy Ounce

Nobody is one hundred percent sure from when or where the Troy weight system originated, but it is most commonly believed that the name is derived from Troyes, a French town in the Middle Ages. Troyes featured a trade market where merchants came from all around the globe to buy and sell goods, which meant a single standardised weight system was needed to ensure it would be easier to do business with those traders from various countries.

The troy ounce that was used by the traders of Troyes is said to have taken its origins from the Roman monetary system. The Romans used large one-pound bronze bars as currency, and these bars could be broken down into twelve pieces called ‘uncia’ or ounce, with each piece weighing 31.10 grams.

The troy ounce was then first used in England in the 15th century by French-born King Henry II, who adjusted the British coinage system to reflect the French troy system. Troy weights became the official standard of measurement for silver and gold in Britain. The U.S. then followed suit in 1828.

Today’s Troy Ounce

The troy ounce (sometimes abbreviated as ‘t oz’ or ‘oz t’) is still used today as the standard unit of measurement for precious metals.

Most precious metals dealers across the globe, like ourselves, list all gold and silver bullion using the troy system. The prices of precious metals are also quoted in troy ounces, as shown in the live pricing on our website. Understanding that a troy ounce is different from a regular ounce, helps you buy in confidence from reputable precious metals dealers, and it is always a good idea to ensure that the dealer you buy from lists the item’s weight in troy ounces, or the corresponding weight in grams, as opposed to just ounces.

Having this universal unit of measurement when dealing with precious metals helps to ensure purity and weight standards remain consistent over time and across the world, which can only be a good thing for investors as we navigate the precious metals market.

Secure Your Gold

Shop Gold

Secure Your Silver

Shop Silver

This blog represents one person’s opinion only. Customers should conduct their own research and take advice before making an investment. We do not offer investment advice.


We use cookies to ensure that we can give you the very best experience. To find out more about how we use cookies, please visit the cookie policy page.