Troy Ounce – How Many Grams? 1 oz is 31.1 g
1 troy ounce (1 oz) is 31.1035 g. Gold and silver are weighed in this unit all over the world, collectible coins and bars included. The ordinary ounce – used in recipes or for parcels – is 28.35 g. Below you will find an ounce-to-gram table, why the two ounces differ, and tips on choosing a coin size.
How many grams in an ounce?
- 1 troy ounce (oz t, 1 oz) = 31.1034768 g, in practice 31.1 g – the unit for precious metals,
- 1 avoirdupois ounce (oz) = 28.3495 g, in practice 28.35 g – used in the US and UK for food, postage, etc.
The difference is almost 2.75 g per ounce, about 10%. When people talk about gold, silver, platinum or coins, an “ounce” always means a troy ounce.
Troy ounces to grams – table
| Troy ounces | Grams | Typical use |
|---|---|---|
| 1/20 oz | 1.56 g | the smallest gold coins |
| 1/10 oz | 3.11 g | popular small gold coins |
| 1/4 oz | 7.78 g | mid-size gold coins |
| 1/2 oz | 15.55 g | smaller silver and gold coins |
| 1 oz | 31.10 g | the most popular coin size |
| 2 oz | 62.21 g | high-relief coins |
| 3 oz | 93.31 g | showpiece collectible coins |
| 5 oz | 155.52 g | large coins and bars |
| 10 oz | 311.03 g | bars and commemorative coins |
| 32.15 oz | 1,000 g (1 kg) | kilo coins and bars |
The other way round: 1 gram = 0.0322 troy oz and 1 kg = 32.15 oz. To convert ounces to grams, multiply by 31.1035 – e.g. 2 oz × 31.1035 = 62.21 g.
Why is it called a troy ounce?
It has nothing to do with Troy. The name comes from the French town of Troyes in Champagne, home to the great medieval trade fairs, where this system of weights was used for precious metals. England adopted it, and today gold and silver prices worldwide are quoted in it. The exact value of 31.1034768 g was fixed in 1959.
Is an ounce of gold the same weight as an ounce of silver?
Yes – 31.1 g. An ounce is a unit of weight, whatever the metal. What differs is the size of the coin: gold is almost twice as dense as silver, so a 1 oz gold coin is usually 30–37 mm across, while a silver one is 37–41 mm.
Watch out for 22-carat (916.7) gold coins such as the Krugerrand or American Eagle: they contain a full ounce of pure gold but, because of the added copper, weigh about 33.9 g. More on gold ounces in 1 oz Gold Coin – Weight, Price and How to Choose, and on precious-metal purity in Gold and Silver Fineness – 999, 925 and 585.
What does “1 oz” on a silver coin mean?
The inscription 1 oz (often “1 oz Fine Silver 999”) means the coin contains one troy ounce of 999 silver – about 31.1 g of pure silver. Specifications usually list two values:
- precious-metal content – how much pure silver or gold the coin contains,
- total weight – which can be slightly higher for alloys below 999.
For 999 silver coins the two are practically equal: 31.1035 g × 99.9% ≈ 31.07 g of pure silver.
Is the price of a 1 oz coin the silver price?
Not quite. A coin's price is the metal value plus a premium – minting, distribution and margin. Bullion coins carry a low premium. Collectible coins add the design, finishing techniques (high relief, gilding, colour), mintage and popularity of the series, which is why two 1 oz coins with the same silver content can cost very different amounts.
1 oz, 2 oz or 1 kg – which size to choose?
- 1 oz – the best place to start: a huge choice of designs and series, an affordable price, easy storage. See 1 oz coins.
- 2 oz and 3 oz – more room for detail, often struck in high relief. See 2 oz coins and 3 oz coins.
- 1 kg (32.15 oz) – monumental coins up to 10 cm across, spectacular as a gift or display piece. See 1 kg coins.
Frequently asked questions
How many grams is 1 ounce?
A troy ounce is 31.1035 g; an ordinary ounce is 28.3495 g.
How many grams in an ounce of gold?
31.1 g of pure gold. 22-carat coins weigh about 33.9 g in total, but also contain 31.1 g of pure gold.
What does oz stand for?
“oz” is the abbreviation of ounce – for precious metals, 1 oz is 31.1 g.
How many ounces in a kilogram?
32.15 troy ounces (or 35.27 ordinary ounces).
How much does an ounce of silver weigh?
The same as an ounce of gold – 31.1 g – but the silver coin is larger, because silver is lighter.
Summary
A troy ounce is 31.1 g, and gold, silver and coins are weighed in it. 2 oz is 62.2 g, 5 oz is 155.5 g and a kilogram is 32.15 oz. If you are looking for your first coin, start with 1 oz – browse our 1 oz silver coins and pick an issue that fits your collection.