Purity Converter
Convert between karat, fineness (parts per thousand), and percentage instantly. Input any value and see the other two update in real time.
Scale: 0 to 24
Parts per thousand
Gold-to-Alloy Ratio75.0% gold
Gold
Alloy
18K Gold - 75% Pure
75% pure gold. The international standard for high-end jewelry and the most popular purity worldwide. Rich gold color, good durability, and widely recognized as a mark of quality.
Conversion Formulas
- Karat to Purity: purity = karat / 24
- Purity to Fineness: fineness = purity x 1000
- Fineness to Percentage: percentage = fineness / 10
ISO 9202 Standard Gold Finenesses
The international standard recognized purity levels for gold alloys.
| Karat | Fineness | Percentage |
|---|---|---|
| 24K | 999 | 99.9% |
| 22K | 916 | 91.67% |
| 21K | 875 | 87.5% |
| 20K | 833 | 83.3% |
| 18K | 750 | 75% |
| 15K | 625 | 62.5% |
| 14K | 585 | 58.33% |
| 12K | 500 | 50% |
| 10K | 417 | 41.67% |
| 9K | 375 | 37.5% |
| 8K | 333 | 33.3% |