How Many Grams in an Ounce of Gold?

If you are wondering how many grams in an ounce of gold, 31.1034768 grams if you are wondering. In gold those are known as troy ounces, which is not the same ounce we use to buy groceries.

In simple calculations, one troy ounce of gold is typically quoted as 31.1035 grams or abusively 31.1 grams. The troy-ounce metric system is often used for precious metals which include gold, silver, platinum etc. One troy ounce is 31.1034768 grams according to the U.S. National Institute of Standards and Technology (NIST).

This difference is particularly essential to keep in mind when you buy gold coins, gold bars and jewelry (see gold price per ounce vs gram).

How Many Grams Are in an Ounce of Gold?

1 troy oz = 31.1034768 grams

For everyday calculations you can regroup using:

1 troy ounce ≈ 31.1035 grams

Numerous gold dealers and also precious-metal websites use the rounded figure of 31.1035 grams to present conversion tables.

Quick Gold Weight Conversion

Gold Weight	Equivalent in Grams
0.1 troy oz	3.1103 g
0.25 troy oz	7.7759 g
0.5 troy oz	15.5517 g
1 troy oz	31.1035 g
2 troy oz	62.2070 g
5 troy oz	155.5174 g
10 troy oz	311.0348 g
20 troy oz	622.0695 g
32.1507 troy oz	1,000 g

What Is a Troy Ounce of Gold?

A troy ounce is the standard weight measure for precious metals. When the gold dealer, bullion market or financial site says gold is at X dollars per ounce – unless they specify otherwise, that ounce typically refers to a troy ounce (31.1 grams), not a household understanding of an ounce (28 g).

A troy ounce holds 480 grains, specifically it is 31.1034768 grams in weight. NIST additionally defines one troy ounce as 20 pennyweights and one pennyweight as 1.55517384 grams.

So, you should convert gold weight using the troy ounce as a standard.

Troy Ounce vs. Regular Ounce

The most frequent blunder calculating gold weight is that it is assumed every ounce holds 28.35 grams or so.

That is indeed a common avoirdupois ounce, the mass-unit used to weigh most foods, household goods, packages and many everyday items. Gold uses the troy ounce which has more grams.

Type of Ounce	Grams	Common Use
Troy ounce	31.1034768 g	Gold and other precious metals
Regular ounce	28.3495231 g	Food and everyday products
Difference	2.7539537 g	Troy ounce is heavier

An ounce in Troy measures about 9.7% more than a regular ounce.

Thus, when calculating the weight or value of gold, 31.1035 grams per troy ounce is used and not the commonly confused 28.35 grams.

Why Is Gold Measured in Troy Ounces?

The precious-metals industry uses the Troy-weight system as a base standard for metal trading and pricing. Although gold bullion products can be expressed in troy ounces, grams, kilograms or other units, international gold prices are still quoted in “troy oz”.

So, if we took 1 oz gold as an example, it generally refers to one troy ounce. That works out to a total precious-metal weight of about 31.1035 grams, depending on the purity and other details in the specifications for each product.

This distinction is critical, especially when we compare products across sellers. An ounce is not necessarily a troy ounce, and it can not be relied on to be interchangeable.

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Gold Ounce to Gram Conversion Table

Troy Ounces of Gold	Grams of Gold
0.01 oz	0.3110 g
0.05 oz	1.5552 g
0.10 oz	3.1103 g
0.25 oz	7.7759 g
0.50 oz	15.5517 g
1 oz	31.1035 g
1.5 oz	46.6552 g
2 oz	62.2070 g
3 oz	93.3104 g
4 oz	124.4139 g
5 oz	155.5174 g
10 oz	311.0348 g
20 oz	622.0695 g
32.1507 oz	1,000 g

How to Convert Gold Ounces to Grams

Converting troy ounces to grams is simple.

Formula

Grams = Troy Ounces × 31.1034768

For example, if you have 3 troy ounces of gold:

3 × 31.1034768 = 93.3104304 grams

So, 3 troy ounces of gold weigh approximately 93.31 grams.

For a 10-ounce gold bar:

10 × 31.1034768 = 311.034768 grams

Therefore, a 10 troy-ounce gold bar contains approximately 311.03 grams of total weight.

How to Convert Grams of Gold to Troy Ounces

You could also convert grams back into troy oz.

Formula

Troy ounces = Grams ÷ 31.1034768

Let say you have 100 grams of gold as an example:

3.2151 troy ounces = 100 ÷ 31.1034768

Thus 100 grams of gold is equal to about 3.215 troy ounces.

Gold in Grams	Approx. Troy Ounces
1 g	0.03215 oz
5 g	0.16075 oz
10 g	0.32151 oz
20 g	0.64292 oz
31.1035 g	1 oz
50 g	1.60754 oz
100 g	3.21507 oz
250 g	8.03768 oz
500 g	16.07554 oz
1,000 g	32.15075 oz

How Much Does a 1-Ounce Gold Bar Weigh in Grams?

According to the troy-ounce measurement, 1 troy-ounce gold bar = 31.1034768 grams

So in everyday descriptions, it is often called 31.1 grams. But note: when a product is not 100% pure, then the total physical weight and amount of pure may vary.

As an example, a gold item with 99.99% stated purity contains slightly less fine-gold than it weighs in total. Which is also why weight and purity play a crucial role in assessing any gold piece.

Does Gold Purity Change the Number of Grams in an Ounce?

No. A troy ounce is a measure of weight and does not change according to gold purity.

One troy ounce is always:

31.1034768 grams

What changes is how much pure gold and silver are in that total weight.

Product Purity	Total Weight	Approx. Fine Gold Content
99.99%	1 troy oz	31.1004 g
99.90%	1 troy oz	31.0724 g
91.67%	1 troy oz	28.5109 g
75%	1 troy oz	23.3276 g

How Many Grams Are in a Gold Bar?

Golden bars can be found in different common designs. The typical weights are 1 gram, 5 grams, 10 grams, 20 grams, 1 troy ounce, and so on:

Gold Bar Size	Approx. Grams	Approx. Troy Ounces
1 g	1 g	0.0322 oz
5 g	5 g	0.1608 oz
10 g	10 g	0.3215 oz
20 g	20 g	0.6430 oz
1 oz	31.1035 g	1 oz
50 g	50 g	1.6075 oz
100 g	100 g	3.2151 oz
250 g	250 g	8.0377 oz
500 g	500 g	16.0755 oz
1 kg	1,000 g	32.1507 oz

What Is the Difference Between a Gold Ounce and a Gram?

Of course, both a gram (g) and a troy ounce (oz), are simply two different units to measure weight.

A troy ounce is far larger than one gram:

1 onza troy equivale a 31.1034768 gramos

Therefore:

1 gram =  0.0321507 troy ounces

You would use this method when asked how one compares small gold bars against larger bullion type products. eg: 10 gram Gold bar ~0.3215 troy ounces.

Why the Troy Ounce Matters When Checking Gold Prices

Gold is often quoted in troy ounces. To have an average price per gram from a quoted gold price, you can divide the price per troy ounce by 31.1034768.

Example

Let’s assume for a moment that gold is priced at $4,000 per troy ounce.

(31.1034768 g = 1oz) $4000 ÷ 31.1034768 ≈ $128.60/ gram

This is just an arithmetic translation of the actual price quote. In practice, the ultimate retail gold prices may vary due to factors related to purity, dealer premiums, fabrication costs, spreads and taxes, etc.

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