Troy Ounce vs. Regular Ounce: How Many Grams in a Troy Ounce and Why Precious Metals Use a Different Pound
One troy ounce equals 31.1034768 grams, usually rounded to 31.1035 g. So if you were wondering how many grams in a troy ounce, the short answer is about 31.1 g, roughly 10 percent heavier than the regular (avoirdupois) unit at 28.3495 g. This gap is why a gold spot quote never matches a kitchen scale reading.
The direct answer in numbers
- 1 oz t = 31.1034768 g exactly (symbol: oz t or ozt)
- 1 avoirdupois oz = 28.349523125 g
- Ratio: 1 oz t is about 1.09714 of the regular unit
- 1 troy pound = 12 oz t = 373.2417 g
- 1 avoirdupois pound = 16 units = 453.592 g
Why precious metals use a different unit
The system traces back to medieval trade fairs at Troyes, a market town in the Champagne region of France. Merchants needed a stable unit for coinage and bullion that travelers from across Europe could trust. Britain adopted this weight for coinage in the 15th century, and the US fixed it as the official measure for gold and silver under the Coinage Act of 1828. The word “ounce” itself comes from Latin “uncia,” meaning one twelfth, which is why the pound here holds 12 units rather than 16.
Troy vs avoirdupois: comparison table
| Unit | Grams | Ratio vs oz t | Typical use |
|---|---|---|---|
| oz t (bullion) | 31.1034768 | 1.000 | Gold, silver, platinum, palladium |
| Regular (avoirdupois) | 28.349523 | 0.9115 | Groceries, postage, body weight |
| Troy pound | 373.2417 | 12.000 | Historic coinage, rare today |
| Avoirdupois pound | 453.5924 | 14.583 | Everyday commerce |
| Kilogram | 1000.000 | 32.1507 | Large bars, central bank reserves |
Handy conversions for bullion buyers
- oz t to grams: multiply by 31.1034768.
- Grams to oz t: divide by 31.1034768.
- oz t to kilograms: divide by 32.1507.
- Regular oz to oz t: multiply by 0.9114583.
Common bullion sizes: a 1/10 oz gold coin is 3.110 g, a 1/4 oz coin is 7.776 g, a 1/2 oz coin is 15.552 g, and a 1 oz coin is 31.103 g. A 10 oz silver bar weighs 311.03 g, and a 100 oz bar weighs 3110.35 g (about 6.86 avoirdupois pounds).
How the system applies to gold, silver, platinum, and palladium
Every major spot quote, futures contract, and bullion invoice prices these four metals per oz t. LBMA good delivery bars, COMEX contracts, and mint products from the US Mint, Royal Canadian Mint, and Perth Mint all use this unit. A .999 fine silver round stamped “1 oz” means one oz t. Weigh that same round on a kitchen scale in regular mode and it reads about 1.097, not 1.000. That confuses plenty of first-time sellers.
Common mistakes when buying or selling bullion
- Using a kitchen scale on avoirdupois mode and thinking your coin is overweight.
- Comparing a pawn shop “per oz” quote against a spot price without confirming which unit is meant.
- Assuming 16 units make a troy pound. It’s 12.
- Mixing weight with karat purity. Weight measures mass; karat measures fineness.
- Rounding 31.1034768 down to 30 g on a napkin calc, which underprices a coin by 3.5 percent.
For quick checks, use our USA gold calculator, silver calculator, platinum calculator, or palladium calculator. The precious metals glossary covers the rest of the vocabulary. External references: NIST Office of Weights and Measures and the Royal Mint history.
FAQ
Is there a difference between 1 troy ounce and 1 ounce?
Yes. One weighs 31.1035 g and the other weighs 28.3495 g, so the bullion unit is about 9.7 percent heavier.
What’s 1 troy ounce of gold worth?
It equals the current spot price quoted on LBMA or COMEX. Spot moves constantly, so check a live feed before any transaction.
How much is a troy ounce of .999 silver worth today?
Multiply the current silver spot by 0.999 for near-pure content, then add the dealer premium. Dealers typically add 2 to 5 dollars per coin for rounds and bars.
Why is a pound of gold only 12 oz?
Because gold uses the troy pound, which contains 12 units, not 16. The 12-part pound comes from the Roman libra, which split into 12 unciae.
How many grams in a troy ounce of silver or platinum?
Exactly the same as gold: 31.1034768 g. The unit is a measure of mass, so it doesn’t change with the metal being weighed.
Is this weight system used anywhere outside precious metals?
Rarely. Gunpowder and some gemstones once used it, but today the unit survives mainly for bullion, jewelry fineness, and historic coin grading.
Bottom line: if you’re buying or selling gold, silver, platinum, or palladium, always confirm the quote is per oz t (31.1035 g) and not the regular unit. That one conversion protects roughly 10 percent of your money every trade.
