A troy ounce is the unit used to price precious metals on world markets and equals 31.1035 grams. In India gold is sold and quoted by the gram or per 10 grams, so the troy ounce matters mainly when you compare Indian rates with the international price.
Ask a jeweller in Mumbai or Chennai for the gold rate and you will hear a price per gram or per 10 grams, never per ounce. The troy ounce still sits behind those numbers, because the international gold price is set per troy ounce in US dollars.
Troy ounce, gram and 10 grams
The troy ounce is not the ounce used for food and parcels. That avoirdupois ounce weighs 28.35 g, so a troy ounce is about 10% heavier. When a coin is described as "1 oz", it always means one troy ounce of fine metal.
| Weight | Grams | Troy ounces |
|---|---|---|
| 1 gram coin | 1 | 0.0322 |
| 10 gram coin or bar | 10 | 0.3215 |
| 1 troy ounce | 31.1035 | 1 |
| 100 gram bar | 100 | 3.215 |
| 1 kilogram bar | 1,000 | 32.15 |
Indian benchmarks follow the gram. The India Bullion and Jewellers Association (IBJA) publishes gold rates per 10 grams and silver rates per kilogram, and also shows the price of 1 gram. That is why most Indian coins and bars come in gram sizes (1 g, 5 g, 10 g, 100 g) rather than in ounces.
From a price per ounce to a price per 10 grams
Divide the price per troy ounce by 31.1035 to get the price per gram, then multiply by 10. Fixed-number example: if gold were 3,11,035 rupees per troy ounce, one gram would cost 10,000 rupees and 10 grams 1,00,000 rupees. These are round illustration numbers. For the real figure, use our gold price per gram in INR or, for larger amounts, the gold price per kilogram. The way the dollar price per ounce turns into a rupee rate is covered in our entry on the spot price.
Gross weight and fine weight
What you pay for is the fine weight: the pure metal inside. The gross weight includes any alloy. Two 10 gram coins can hold different amounts of gold:
- A 10 g coin of 999 purity holds 9.99 g of fine gold.
- A 10 g coin of 22 karat (916) gold holds 9.16 g, with copper or silver making up the rest.
The gap is 0.83 g, or about 8% less gold for the same weight on the scale. So compare the price per gram of fine metal, not per gram of the object. More on purity marks in fineness and carat.
Silver works the same way. A 1 kg silver bar holds 32.15 troy ounces of silver, and the silver price per kilogram follows the same unit IBJA uses. Small sizes carry a higher premium over spot per gram, which you can check in our list of the cheapest gold coins in India.
Related terms
Fineness Spot Price Premium Over Spot Carat or Karat (Gold Purity)
FAQ
How many grams are in a troy ounce?
One troy ounce equals 31.1035 grams, so 10 grams of gold is about 0.32 troy ounces.
Why are gold rates in India quoted per 10 grams?
Indian benchmarks are gram based: IBJA, for example, publishes its gold rates per 10 grams and its silver rate per kilogram.
Does a 10 gram 22 karat coin contain 10 grams of gold?
No. At 916 purity it contains 9.16 g of fine gold; only a coin of 999 purity comes close to its full weight in gold.