How to Calculate Gold Value by Weight and Karat
Gold value depends on weight, purity, and the spot price basis. Equal weight does not mean equal value if the karat is different.
Written by Calzivo Editorial Team
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To calculate gold value, convert the item weight into grams, multiply by the selected purity, then value the pure gold content using the spot price per troy ounce. The key is to value pure gold content, not the full item weight.
Use the calculators: Use the Gold Calculator for raw gold value or the Scrap Gold Calculator for a payout estimate after fees.
The basic formula path
- Convert entered weight to grams.
- Apply karat purity, such as 18K = 75% gold.
- Convert spot price per troy ounce into price per gram.
- Multiply pure gold grams by price per gram.
If you enter 10 g of 18K gold and use a spot price of $2,000 per troy ounce, first convert 18K to 75% purity. Pure gold content is 10 x 0.75 = 7.5 g. The spot price per gram is about $2,000 / 31.1035 = $64.30, so the raw gold value estimate is about 7.5 x $64.30 = $482.25 before any buyer deductions.
Why equal weight can have different value
A 10 g 24K item contains almost 10 g of pure gold. A 10 g 14K item contains about 5.83 g of pure gold. The total weight is the same, but the gold content is different.
Spot price basis
Gold spot prices are commonly quoted per troy ounce. The calculators convert that price into a gram basis using 31.1034768 grams per troy ounce.
Gold value is based on pure gold content, so weight, karat, and spot price all matter.
Use the tool instead
Use the matching calculator when you want to plug in your own numbers and get a result faster.
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