If you have ever wondered why a “1 oz” silver coin feels heavier than an ounce on your kitchen scale, you have run into one of the most common points of confusion in precious metals: the difference between a troy ounce and a regular ounce. Here is everything you need to know.
What Is a Regular Ounce?
The ounce used for everyday goods in the United States is the avoirdupois ounce. It is part of the system in which 16 ounces make one pound, and it is used to weigh food, packages and most other products. One avoirdupois ounce equals 28.3495 grams.
What Is a Troy Ounce?
A troy ounce is the standard unit for weighing precious metals such as gold, silver, platinum and palladium. One troy ounce equals 31.1035 grams. The unit is named after Troyes, a French market town that was an important trading center in the Middle Ages. It was later adopted in Britain and is still the global standard for precious metals today.
The Key Difference
A troy ounce is about 10% heavier than a regular ounce. Because precious metals are priced by weight, that difference matters: when you see the spot price of gold or silver, it is always quoted per troy ounce.
| Unit | Grams | Used for |
|---|---|---|
| Avoirdupois ounce (oz) | 28.3495 g | Everyday goods, food, shipping |
| Troy ounce (ozt / t oz) | 31.1035 g | Gold, silver, platinum, palladium |
Quick Conversions
- 1 troy ounce = 31.1035 grams
- 1 troy ounce ≈ 1.097 avoirdupois ounces
- 1 avoirdupois ounce ≈ 0.911 troy ounces
- 1 kilogram ≈ 32.15 troy ounces
- 12 troy ounces = 1 troy pound (unlike the 16-ounce everyday pound)
Why the Industry Still Uses Troy Ounces
- One global standard: mints, refiners and markets around the world quote prices and weights the same way, which keeps trading clear and fair.
- Long history: the troy system has been used for precious metals for centuries, so it is deeply built into how the market works.
- Precision: using a single, well-defined unit avoids costly mistakes when large amounts of metal change hands.
The only real drawback is unfamiliarity: people outside the precious metals world rarely use troy ounces, which is why the difference can catch new buyers by surprise.
Frequently Asked Questions
Is gold sold by the ounce or the troy ounce?
By the troy ounce. When a coin or bar is labeled “1 oz” in the precious metals market, it means one troy ounce of metal.
Can I weigh my coins on a kitchen scale?
You can, as long as the scale can switch to grams or troy ounces and is accurate enough. A precise digital scale that reads to at least 0.01 gram is best for checking coins and small bars.
Are silver, platinum and palladium also measured in troy ounces?
Yes. All the major precious metals are weighed and priced in troy ounces.
Does “1 oz” on a coin mean total weight or metal content?
On bullion products it normally refers to the pure metal content. A coin with a purity below .999 (for example, a 22-karat gold coin) will weigh slightly more than one troy ounce in total so that it still contains a full ounce of gold.
The Bottom Line
Whenever you buy or sell precious metals, think in troy ounces. Knowing that a troy ounce is 31.1 grams — about 10% heavier than an everyday ounce — will help you compare prices accurately and understand exactly what you are getting.