What Is a Troy Ounce? Troy Ounce vs Ounce, Grams and Gold Value
The troy ounce in one sentence
A troy ounce is the unit used to weigh precious metals, equal to exactly 31.1034768 grams. When you see "gold at X dollars", it always means X dollars per troy ounce of pure gold.
Troy ounce vs regular ounce
The ounce used for food and parcels in the United States is the avoirdupois ounce, 28.3495 grams. The troy ounce is about 9.7% heavier. The difference matters: if you weigh a gold item on a kitchen scale in ounces and multiply by the gold price, you will undervalue it by almost a tenth. Weigh in grams instead, or convert.
Confusingly, the troy pound is lighter than the ordinary pound: it has only 12 troy ounces (373.24 g), while the avoirdupois pound has 16 ordinary ounces (453.59 g). Troy pounds are rarely used today.
Conversion table
| 1 troy ounce equals | Value |
|---|---|
| Grams | 31.1035 g |
| Avoirdupois ounces | 1.0971 oz |
| Pennyweights (dwt) | 20 dwt (1 dwt = 1.5552 g) |
| Grains | 480 grains (1 grain = 64.8 mg) |
| Tolas | 2.6667 tolas (1 tola = 11.6638 g) |
| Kilograms | 0.0311 kg (1 kg = 32.1507 troy oz) |
Handy shortcuts: 1 kilogram is about 32.15 troy ounces, and 100 grams is about 3.215 troy ounces. For any other conversion use our gold unit converter, and read our guide to gold weight units for tolas, taels and more.
What one troy ounce of gold is worth today
| Currency | 1 troy ounce | 1 gram |
|---|---|---|
| US dollar | 4,122.20 USD | 132.53 USD |
| Euro | 3.668,40 EUR | 117,94 EUR |
| British pound | 3,059.98 GBP | 98.38 GBP |
| Canadian dollar | 5,757.56 CAD | 185.11 CAD |
| Australian dollar | 5,885.05 AUD | 189.21 AUD |
| Indian rupee | 390,044 INR | 12,540.18 INR |
| Mexican peso | 76,769.10 MXN | 2,468.18 MXN |
| UAE dirham | 15,138.79 AED | 486.72 AED |
These are spot values for pure (24K) gold. Coins and bars sell for a little more, and jewelry contains less gold than its weight — see the 18K and 14K price pages.
Where the name comes from
The name is usually traced to Troyes, a town in Champagne, France, whose medieval trade fairs drew merchants from across Europe. The weights used there spread through trade, and England adopted troy weight for precious metals and coinage in the Middle Ages. The grain — originally the weight of a grain of barley or wheat — is the base: 480 grains make a troy ounce. In 1959 international agreement fixed the grain at exactly 64.79891 milligrams, which is why the troy ounce has such a precise gram value.
Why gold is still priced in troy ounces
Tradition and market convention. The London bullion market, New York futures and most dealers worldwide quote in US dollars per troy ounce, and investment coins are made in troy-ounce sizes: the Maple Leaf, Krugerrand, Philharmonic and American Eagle each contain exactly one troy ounce of gold. Local markets also use grams (Europe, Latin America), tolas (India, Pakistan, the Gulf) and taels (China, Hong Kong), and our site shows prices in all of them.
Fine ounce vs gross weight
A "fine ounce" means one troy ounce of pure metal. A 22K coin such as the Krugerrand weighs 33.93 g in total but contains one fine troy ounce of gold; the rest is copper. When comparing products, always look at the fine gold content, not the total weight. Our gold coin guide lists both for every popular coin.