Gold Purity Calculator
Convert between karat, percentage purity and millesimal fineness, compute the pure-gold content and live value of any item, and design alloy mixes — all updated from the current spot price.
Karat ⇄ Purity ⇄ Fineness
Drag the slider or type a karat value (1–24) to see all three standard purity expressions.
Pure Gold Content & Live Value
Enter the gross weight of your item and its karat to see the actual pure-gold mass and what it's worth at today's spot price.
Alloy Blender
Mix two karats to see the resulting purity — useful for refiners, casters and jewelers planning a melt.
Hallmark & Karat Reference
Standard gold hallmark stamps you'll find inside jewelry and bullion, with their typical commercial use.
| Stamp | Purity | Typical use |
|---|---|---|
| 999 / 24K | 99.9% | Investment bars & bullion coins |
| 990 | 99.0% | High-purity jewelry (Asia) |
| 916 / 22K | 91.67% | Indian / Middle-East jewelry, Krugerrand |
| 875 / 21K | 87.5% | Gulf jewelry standard |
| 833 / 20K | 83.3% | Vintage European pieces |
| 750 / 18K | 75.0% | Premium fine jewelry, watches |
| 585 / 14K | 58.5% | Everyday US/EU jewelry |
| 417 / 10K | 41.7% | Affordable US jewelry, class rings |
| 375 / 9K | 37.5% | UK / commonwealth jewelry |
| 333 / 8K | 33.3% | Lowest legal gold (Germany) |
Live Value per Gram by Karat (USD)
| Karat | Fineness | Purity | Price / g | Price / oz |
|---|---|---|---|---|
| 24k | 999 | 100.00% | $133.29 | $4,145.67 |
| 22k | 916 | 91.67% | $122.18 | $3,800.34 |
| 21k | 875 | 87.50% | $116.63 | $3,627.46 |
| 20k | 833 | 0.00% | $0.00 | $0.00 |
| 18k | 750 | 75.00% | $99.96 | $3,109.26 |
| 14k | 585 | 58.33% | $77.75 | $2,418.17 |
| 10k | 417 | 41.67% | $55.54 | $1,727.50 |
| 9k | 375 | 37.50% | $49.98 | $1,554.63 |
| 8k | 333 | 33.30% | $44.38 | $1,380.51 |
Frequently Asked Questions
What does karat mean?▾
Karat (k) is the share of pure gold in parts of 24. 24k = pure gold; 18k = 18/24 = 75% gold + 25% alloy metals (typically silver, copper, palladium or zinc).
What is the difference between karat and millesimal fineness?▾
They express the same thing in different units. Fineness is parts per thousand: 18k = 750, 14k = 585, 22k = 916. Bullion bars are usually stamped with fineness rather than karat.
How do I calculate gold jewelry value?▾
Multiply gross weight × purity to get pure-gold grams, then multiply by the live spot price per gram in your currency. Subtract refining/dealer fees if you're selling scrap.
Why is 22k more common in India and 14k in the US?▾
22k holds value as near-bullion jewelry and is preferred for investment and weddings. 14k is harder and more scratch-resistant, better suited to everyday Western jewelry.
Can two karats be melted to make a target karat?▾
Yes — use the Alloy Blender above. Mass-weighted average of the input purities gives the resulting karat.