How Many Grams in an Ounce of Gold?

Gold is measured in troy ounces, with each ounce of gold equating to about 31.105 grams. If you’re new to the world of precious metals, understanding the difference between troy ounces, standard ounces, and grams is essential when buying, selling, or valuing your bullion pieces.

In this article, we’ll go beyond how many ounces are in a gram of gold to look at troy ounces, why it’s important to understand gold weight measures, and other units of measure used for gold.

How much is an ounce of gold in grams?

An ounce of gold weighs about 31.1035 grams (or 31.1034768 grams to be exact). This might seem confusing for those who know that a standard ounce weighs 28.35 grams. That’s because gold uses a special type of ounce called the troy ounce, which is different to the standard ounce most of us are familiar with (called the avoirdupois ounce).

The troy ounce has been the official measurement for gold, silver, and other precious metals for hundreds of years and the majority of gold bullion coins today are made to weigh exactly one troy ounce.

To convert gold from grams to troy ounces, simply multiply the number of grams by 0.03215.

What is a troy ounce?

A troy ounce is the standard unit used for weighing precious metals like gold, silver, and platinum. It’s different from the regular ounce that measures everyday items like food or mail.

Before switching to the metric system, Britain used the avoirdupois system, where 16 ounces made up one pound. This system worked well for everyday goods, but when it came to trading gold and silver it wasn’t precise enough. Merchants needed a more consistent standard and in the 1400s, the troy system was introduced.

The troy ounce became the official measurement for precious metals in Britain during the 1500s and it was adopted by the United States in the 1800s. It remains the global standard for valuing gold, silver, platinum, and palladium today.

Read More: Troy Ounce: Definition, History, and Conversion Table

History of the troy ounce

The exact origins of the troy ounce are still debated, but the most widely accepted theory points towards the medieval French market town of Troyes. This bustling trade centre attracted merchants from across Europe and Britain, and a standard measurement was needed to ensure accuracy and alignment across all traders.

Intriguingly, the troy system of measure is similar to an ancient Roman weight system where an uncia, the Latin word for ounce, represented one-twelfth of a Roman pound (libre). The Roman pound weighed about 327 grams, meaning each uncia was roughly 27 grams. Although not an exact match to the troy ounce, this division into twelfths (rather than sixteenth as with the avoirdupois system) likely influenced the later development of the troy standard. This connection suggests that the roots of the troy ounce could stretch as far back as the Roman Empire itself.

In the early 1400s, the troy system made its way to England and became the official standard for weighing gold and silver. In 1527, King Henry VII formally incorporated the troy ounce into the British Imperial System and set a consistent benchmark for precious metals trading.

When the United States later established its own currency system, the Coinage Act of 1828 solidified the use of the troy ounce as the official measurement for gold and silver coins.

What’s the difference between an ounce and a troy ounce?

The troy ounce and avoirdupois ounce are both units of measure, but they’re used in different contexts and are not equal in weight. The troy ounce is used to measure precious metals and is slightly heavier than the everyday ounce, which is used to measure grain and other everyday items.

One troy ounce is approximately 31.1035 grams, while one avoirdupois ounce is approximately 28.3495 grams. This means that a troy ounce is about 10% heavier than a regular ounce.

The avoirdupois ounce is part of the broader avoirdupois system which divides a pound into 16 ounces. On the other hand, the troy system divides a troy pound into only 12 troy ounces.

It’s important to be aware of the differences between these two measurements – confusing the two can lead to significant miscalculations when buying, selling, or valuing your precious metals holdings. More on that in the next section.

Why it’s important to understand gold weights

Pricing and accuracy is essential in the gold market, and if you use the wrong unit of measure you can make some seriously costly mistakes.

To reiterate, the troy ounce is universally used in the precious metals market when quoting prices and weights for gold, silver, platinum, and palladium. Unlike an avoirdupois ounce, which weighs 28.35 grams, the troy ounce is about 10% heavier at 31.1035 grams. Getting confused between the two can result in major pricing errors, especially if you’re buying or selling in bulk.

For example, most gold bullion coins (like the American Gold Eagle, Gold Britannia, and Gold Krugerrand) are minted to weigh exactly one troy ounce. But some gold coins, like the Chinese Gold Panda, are measured in grams. So a 30-gram Gold Panda coin weighs slightly less than a troy ounce (about 0.9645 troy ounces). If you’re comparing prices between different coins, it’s important to be aware of the different units and adjust your calculations as needed.

When it comes to gold, the larger the quantity of gold you purchase, the lower per-unit cost – just like when you buy in bulk at a wholesale store. Here’s how gold pricing scales by weight:

• Buying gold bars in grams is generally more affordable for entry-level buyers but comes at a higher cost per unit
• Buying gold in ounces provides better value than grams
• Buying gold bars by the kilogram offers the best value per unit, but it comes at a significant upfront investment.

To give you an example, let’s say a 1-gram gold bar costs about $125. If you were to buy 31 individual 1-gram gold bars, you’d be paying about $3,875 instead of $3,550 for a single 1-oz gold bar. That means it’s costing you hundreds of dollars more to buy essentially the same amount of gold.

See: Pros and Cons of Buying Gold Bars vs Gold Coins

What other measurements are used for gold?

Troy ounces and grams are the most common way to measure gold, but sometimes other units are used depending on the region and type of transaction.

One important gold measure to know is fractional gold. Fractional pieces are measured as fractions of a gram or ounce, such as ½ gram, 1/10 oz, or ¼ oz coins or bars. These smaller units are often more affordable for first-time buyers, but again, they carry a higher cost per unit compared to buying larger gold bars or coins.

Another less commonly used measurement is the pound. One important thing to note here is that a troy pound equals 12 troy ounces (about 373 grams), unlike the standard pound which weighs 454 grams. This means that even though a troy ounce is heavier than an avoirdupois ounce, a troy pound is actually lighter.

Gold can also be measured in:

• Kilograms (kg): Common for large transactions. One kilogram equals about 32.1507 troy ounces.
• Tolas: Mainly used in South Asia. 1 tola equals about 11.6638 grams or 0.375 troy ounces.
• Carats (ct): Used to measure purity rather than weight. One carat equals 0.2 grams.
• Pennyweights (dwt): Mostly used in North America for jewellery and scrap gold. 1 troy ounce equals 20 pennyweights.

Gold measurement conversion table

The below table compares the different units of measure used for gold and other precious metals.

UNIT OF MEASURE	MEASUREMENT EQUIVALENT IN TROY OUNCES	MEASUREMENT EQUIVALENT IN GRAMS
Troy Ounce (ozt or oz)	1	31.1035
Gram (g)	0.0321	1
Kilogram (kg)	32.1507	1,000
Avoirdupois pound (lb)	14.5833	453.5924
Carat (ct)	155.5174	5
Tola (t)	1.2056	11.6638

Learn More: What is Gold Carat?

What else plays a role in gold prices?

The metal content of gold pieces plays a major role in its price, but it’s not the only factor to consider. The type and format of gold can also impact its value (e.g. bars, rounds, or coins).

Gold bars and rounds are generally valued close to the current spot price of gold, plus a small dealer’s premium to cover manufacturing and distribution costs. But gold coins tend to carry a higher price tag, even if they contain the same amount of precious metal.

One reason why gold coins cost more than gold bars or rounds is sovereign mint certification. Gold coins are issued by official government mints – like the Royal Mint, United States Mint, or Austrian Mint – and come with an official guarantee of weight, purity, and authenticity. For example, the U.S. government backs that every American Gold Eagle coin contains exactly 91.67% gold, 3% silver, and 5.33% copper.

Sovereign coins sometimes also carry additional value because of their historical significance, collectibility, and global recognition. Some people consider owning a coin issued by a national mint as being a sign of prestige and historical importance. In some cases, certain coins become sought-after collectibles that command much higher premiums than their intrinsic metal value.

See: What Drives the Price of Gold?

Invest in gold bullion with StoneX Bullion

Now that you know how to accurately weigh, measure, and value gold bullion, you can start building your collection. At StoneX Bullion, we stock a wide range of investment-grade gold, silver, platinum, and palladium bars and coins from the most prestigious sovereign mints in the world.

Browse our range and start preserving your wealth with precious metals today.