How Many Grams Are In An Ounce of Gold?

Although the name might throw some people off at first, the standard measurement for precious metals (troy ounce - ozt) isn't equal in weight to the imperial ounces (oz) we commonly use here in the United States.

The standard ounce ( oz. ), also called the avoirdupois ounce, is a system commonly used in the US for measuring foods but not precious metals. While an imperial ounce (oz) is equal to 28.35 grams, one troy ounce (troy oz) is equal to 31.1034768 grams.

Hence, one ounce of gold should therefore contain 31.103 grams of gold. When gold traders mention ounces, they usually mean the troy ounce, not the standard ounce measurement.

Keep reading to find out more about the tradition of using Troy ounces in the precious metals industry and to fully understand the conversion between a troy ounce of gold into grams.

Why Does Oz vs Ozt Matter?

If you are calculating your gold bullion prices on an avoirdupois ounce basis instead of a troy ounce basis, then your math will be off by approximately 10%. In the gold industry, this is a big discrepancy in gold weights which will reflect on the value of the product.

Because the industry uses Troy ounces as a standard measurement system, it can get confusing when someone asks "how many ounces?" because they are technically referring to "how many troy ounces?"

Just know that in the industry, gold traders work off a troy-ounce unit when speaking of silver, platinum, gold, and other precious metals. This unit is often used as a reference for the gold price and value, which is usually quoted in pounds, dollars, or euros per troy ounce.

When it comes to comparing gold prices and sizes, it is crucial for investors to understand exactly how much gold they have in their hands when trading. This could also help you calculate the best prices for different products, especially if you are comparing between products measured in grams versus one measured in Troy ounces.

For instance, since 2016, Chinese Gold Panda coins are measured in grams. If you are comparing prices with other coins based on the Troy oz system, do not make the mistake of using the avoirdupois ounce in the conversion. Gold Pandas weigh 30 grams, or 0.9645 Troy ounces. That means you should expect a slightly lower price for the Gold Pandas when compared to other One-Troy-Ounce coins.

Read more information on how to do precise calculations below.

History of Troy Ounces for Precious Metals

Even though no one can point to a specific year when or a specific place where the troy-ounce system was born, its name seems to be taken from an old trade market town in France called Troyes.

Given the strategic position of the city, the market was constantly visited by people from all over Europe. Creating a standard unit for precious metals would allow everyone to agree on a standard gold price.

Interestingly, the idea of the troy ounce might be even older than the Troyes trade market in France. Today, a troy ounce is equal to exactly one-twelfth of a troy pound. And the bronze bars used by the Romans in the Ancient Roman Empire weighed exactly 1 troy pound.

Coincidence? Many don't think so. Several people argue that the French might have taken the Roman weight as a baseline when coming up with their own system of standard weights.

Troy ounce system in England and the US

Throughout the years, the measurement system from Troyes spread around Europe with slight alterations. It was in England, in the early 1400s, that the standard weight for precious metals we use today was first officially established.

King Henry V approved a statute in 1527 defining the British Imperial system of measures, which included the British Troy oz as the standard scale for gold and silver.

The United States of America inherited the British tradition and established the Troy system as the official weight for gold and silver with the Coinage Act of 1828.

How Many Grams In An Ounce Of Gold?

First and foremost, the world's most common gold measurements consist either of troy ounces or grams.

Every 1 troy ounce of .999 fine gold weighs precisely 31.1034768 grams of pure gold.

For this real-world video example above, we used a $12 dollar two-decimal point digital scale to weigh some common 24 karats 1 troy ounce gold ingot products.

To begin, we weigh how many grams are in this .9999 fine 1 oz PAMP Suisse gold bar.

1 oz PAMP Suisse Lady Fortuna Gold Bar Reverse

Most Common Gold Bullion Coins: Weights and Measures

Up next, we weigh a common One Troy Ounce Canadian Maple Leaf Coin comprised of .9999 fine gold bullion.

1 oz Canadian Gold Maple Leaf

Note that it is common for both government and private gold mint products to err on the heavy side by containing an extra 100th grams or two of gold.

It is also very unlikely you will ever find genuine gold ingot products which do not contain a minimum of the troy ounce unit or weight stamped upon them.

When comparing prices, one additional important point about weighing common gold bullion coins is to consider their purity. Two of the most popular and widely circulated fine gold coins are 22k gold, the South African Gold Krugerrand coin being one of them:

1 oz South African Gold Krugerrand

The highly popular 1 oz American Gold Eagle coin.


To end the video, we weigh the world's most popular gold coin by sales volume: The American Gold Eagle coin.

1 oz American Gold Eagle

This 22k 1 oz Gold Eagle coin is made with an over .916 gold purity, yet the gold coin is also mixed with additional silver and copper inputs to make it more dent and warp resistant.

To ensure the gold weight in grams of 22k gold coins, we simply multiply 33.95 grams by its .916667 purity resulting in approximately 31.12 grams of the precious metal contained.

We hope this article and video helped you better understand precisely how many grams are in a troy ounce of gold bullion.

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James Anderson
James Anderson
Senior Market Analyst & Content

A bullion buyer years before the 2008 Global Financial Crisis, James Anderson is a grounded precious metals researcher, content creator, and physical investment grade bullion professional. He has authored several Gold & Silver Guides and has been featured on the History Channel, Zero Hedge, Gold-Eagle, Silver Seek, Value Walk and many more. You can pick up Jame's most recent, comprehensive 200+ Page book here at SD Bullion.

Given that repressed commodity values are now near 100-year low level valuations versus large US stocks, James remains convinced investors and savers should buy and maintain a prudent physical bullion position now, before more unfunded promises debase away in the coming decades...