How Gold Is Measured
Understand troy ounces, grams, kilograms, purity and the common units used in the gold market.
Gold is measured by both weight and purity. A weight alone does not tell you how much pure gold is present, and a purity number alone does not tell you how much metal you own.
Weight units
The professional precious-metals market commonly uses the troy ounce. One troy ounce is about 31.1035 grams. This is different from the avoirdupois ounce used for many everyday goods.
Retail gold is also sold in grams, kilograms and fractional troy-ounce sizes. Always confirm which unit a seller is using before comparing prices.
Purity systems
Purity can be expressed as fineness or karat. Fineness often appears as a decimal or parts per thousand, while karat describes pure gold as a fraction of 24 parts.
For example, 24-karat gold is generally used to describe very high-purity gold, while lower-karat jewelry contains more alloying metals.
Comparing products correctly
To compare two gold products, first calculate the amount of pure gold in each product, then compare the total purchase price. Premiums and fees can make two pieces with the same gold content cost very different amounts.
Accurate scales and reliable assay information matter when high-value transactions are involved.
Key takeaway
The best gold decisions usually come from understanding the product, the price components, the risks, the seller or custodian, and the purpose the gold serves in your plan. Compare multiple sources and verify important details independently.