Troy Ounce vs. Ounce vs. Gram: Precious Metal Units Explained
Why gold is priced in troy ounces, how they differ from regular ounces, and how to convert between grams, kilos, tolas, taels and baht with confidence.
Gold, silver, platinum and palladium are almost always quoted in troy ounces — but your bar may be stamped in grams, your grandmother’s bangles may be measured in tolas, and your kitchen scale shows regular ounces. Knowing how they relate makes every price, bar and piece of jewelry easy to compare.
The troy ounce is not a regular ounce
| Unit | Grams |
|---|---|
| 1 troy ounce (oz t) | 31.1035 g |
| 1 regular (avoirdupois) ounce | 28.3495 g |
A troy ounce is about 9.7% heavier than the ounce used for food and parcels. If you weigh a 1 oz gold coin on a kitchen scale set to ounces, it will read roughly 1.1 oz — and it is not overweight.
The system dates back to medieval trade fairs in Troyes, France, and is still the global standard for bullion. The London Bullion Market, COMEX and most dealers quote prices per troy ounce.
Fun fact: a troy pound (12 troy ounces, 373.24 g) is lighter than a regular pound (16 ounces, 453.59 g), even though a troy ounce is heavier than a regular ounce.
Converting a price per ounce to grams and kilos
- Price per gram = price per troy ounce ÷ 31.1035
- Price per kilogram = price per troy ounce × 32.1507
- Price per troy ounce = price per gram × 31.1035
For example, if gold trades at $3,110.35 per troy ounce, that is exactly $100 per gram and $100,000 per kilogram.
Common bar and coin sizes
| Product | Weight |
|---|---|
| 1 g bar | 0.0322 oz t |
| 1 oz coin or bar | 31.1035 g |
| 100 g bar | 3.215 oz t |
| 10 oz bar | 311.035 g |
| 1 kg bar | 32.1507 oz t |
| LBMA “Good Delivery” gold bar | ~400 oz t (~12.4 kg) |
Regional units you will meet
Many markets still trade in traditional units. Their exact size depends on the country, so always check which definition a dealer is using.
- Tola — 11.6638 g (0.375 oz t). Widely used in India, Pakistan, Nepal and the Gulf. The popular “10 tola” bar weighs 116.64 g.
- Tael — around 37.43 g in Hong Kong’s gold market and 37.5 g in Taiwan; mainland China’s modern market tael is 50 g.
- Baht — Thailand’s gold unit: 15.244 g for bullion and 15.16 g for jewelry.
Smaller units: grains and pennyweights
- Grain — 1 troy ounce = 480 grains (1 grain = 0.0648 g).
- Pennyweight (dwt) — 1/20 of a troy ounce, 1.555 g. Jewelers in the US often price scrap gold per pennyweight.
Quick checklist
- When a price says “oz” for a precious metal, assume troy ounce.
- When your scale says “oz”, it almost certainly means avoirdupois ounce — switch it to grams.
- Convert everything to grams (or everything to troy ounces) before you compare prices.
Let the app do the converting
MetalFolio lets you choose your default weight unit once — grams, ounces and more — and shows every price and every holding in that unit, in any of 30+ currencies.
This article is for information only and is not financial advice.
