What does 24K gold mean?
24K is the reference for nearly pure gold. This tool models it with a 1.000 theoretical factor; an item's actual fineness still depends on its hallmark and test result.
Purity explained
Gold Purity Chart and Karat Guide
Karat tells you how much of an alloy is theoretically gold. Use this quick guide to understand the factors behind 24K, 22K, 18K, and other gold value calculations.
Common gold purity factors
The calculator models purity as karat divided by 24. That gives a transparent estimate of fine-gold content before premiums, labour, testing, fees, or condition are considered.
| Karat | Theoretical factor | Approx. fineness |
|---|---|---|
| 24K | 24/24 = 1.000 | 999–1000 |
| 22K | 22/24 = 0.9167 | 916.7 |
| 18K | 18/24 = 0.7500 | 750 |
| 14K | 14/24 = 0.5833 | 583 |
| 10K | 10/24 = 0.4167 | 417 |
| 9K | 9/24 = 0.3750 | 375 |
- 24K = 24/24 = 1.000 theoretical factor
- 22K = 22/24 = approximately 91.67%
- 18K = 18/24 = 75%
- 14K = 14/24 = approximately 58.33%
- 10K = 10/24 = approximately 41.67%
- 9K = 9/24 = 37.5%
How purity changes a spot estimate
First convert the selected weight into grams, multiply by the 24K spot value per gram, and then apply the selected purity factor. The result is a theoretical spot / melt value estimate, not the price of a piece of jewellery or a guaranteed resale amount.
Fineness and real items
Fineness expresses gold content in parts per thousand: for example, 916.7 is commonly associated with 22K and 750 with 18K. Real products can vary by alloy standard, hallmark, manufacturing, and testing result. A buyer or dealer may also apply a spread, refining cost, labour charge, or margin. Confirm the item's purity independently before using any estimate for a transaction.
Helpful answers
Gold Purity Chart and Karat Guide FAQ
How is 22K gold calculated?
The theoretical factor is 22 divided by 24, or approximately 0.9167. The calculator applies that factor to the 24K spot value for the selected weight.
Is 18K gold 75% pure?
For the transparent theoretical model used here, 18K is 18 divided by 24, or 75%. A physical item's verified fineness and any dealer terms may differ.
Does a purity factor equal a jewellery price?
No. It estimates metal content from spot data. Jewellery price, resale value and dealer offers can include premiums, labour, testing, taxes and margins.