Calculate how much pure gold is contained in an existing gold alloy. Enter the alloy weight, choose a karat or fineness, and calculate fine-gold content, gold purity, fineness and the remaining non-gold alloy weight.
Start with the weight you already have and determine its gold content.
The calculation assumes the entered weight represents the gold alloy. Gemstones and other non-gold materials should not be included in the alloy weight.
Pure gold content is the amount of gold contained within a gold alloy after accounting for its stated purity. Karat and fineness tell you what fraction of the alloy is gold.
This calculator starts with an existing weight and works forward to the amount of fine gold it contains.
For fineness, the equivalent formula is:
18K gold represents 18 parts gold out of 24, which equals 75% gold.
Therefore, 20 grams of 18K gold contains 15 grams of fine gold and approximately 5 grams of other alloy metals.
22K gold contains approximately 91.67% gold.
So 10 grams of 22K alloy contains approximately 9.166667 grams of fine gold under the mathematical karat calculation.
| Karat | Gold Purity | Fine Gold in 10 g Alloy | Non-Gold Portion |
|---|---|---|---|
| 24K | 100% | 10.0000 g | 0 g |
| 22K | 91.67% | 9.1667 g | 0.8333 g |
| 18K | 75% | 7.5000 g | 2.5000 g |
| 14K | 58.33% | 5.8333 g | 4.1667 g |
| 10K | 41.67% | 4.1667 g | 5.8333 g |
| 9K | 37.50% | 3.7500 g | 6.2500 g |
If the gold specification is given as fineness rather than karat, the calculation is just as direct.
For example, 750 fineness means 750 parts gold per 1,000 parts material, or 75% gold.
The result is equivalent to the mathematical 18K calculation because 18K corresponds to 750 fineness.
Pure gold content is not necessarily the same as the weight shown on a jewellery scale.
A finished jewellery item may contain gemstones, enamel, solder, settings or other materials. The calculator assumes the input weight is the weight of the gold alloy itself.
The terms "fine gold" and "pure gold content" refer to the calculated gold portion of an alloy. They are useful when comparing different purity grades on a common weight basis.
For example, two 20-gram items can contain different amounts of fine gold if one is 22K and the other is 18K.
The difference comes entirely from their different gold proportions in this mathematical comparison.
This calculator answers:
The separate Pure Gold Weight Calculator answers the reverse question:
Keeping these directions separate prevents the two calculations from becoming duplicate tools.
Pure gold content can be useful as a starting point for valuation because it establishes the amount of gold in the material. However, gold content alone does not determine the final price of jewellery.
Market gold price, workmanship, gemstones, design, brand, condition, premiums, taxes and the buying or selling market can all affect value.
The calculator supports common gold-weight units including grams, kilograms, troy ounces, tola, pennyweight and grains. The selected unit is converted internally so the purity calculation remains consistent.
This tool performs a mathematical calculation from the stated weight and purity. It does not test the physical composition of the metal.
A karat stamp or fineness mark may provide a stated specification, but mathematical conversion cannot authenticate a physical item.
Where actual composition is uncertain or commercially important, suitable professional testing or assay information should be used.
It calculates the amount of fine gold contained in an existing gold alloy from its weight and stated karat or fineness.
Multiply the alloy weight by the karat divided by 24. For example, 20 grams of 18K gold contains 15 grams of fine gold.
18K gold is 75% gold, so 20 grams contains 15 grams of fine gold under the mathematical karat calculation.
10 grams of 22K gold contains approximately 9.1667 grams of fine gold.
Yes. Divide fineness by 1,000 to obtain the purity fraction, then multiply it by the alloy weight.
No. Total jewellery weight can include alloy metals, gemstones and other materials. Pure gold content represents only the calculated gold portion.
No. The calculation assumes the entered weight is the gold-alloy weight. Gemstones and other materials should be excluded where possible.
No. It calculates gold content by weight. Gold value requires a gold price and may depend on additional factors.