Gold Karat Purity Calculator
Find out how much pure gold is in 24K, 22K, 18K, 14K or 10K gold — as a percentage, a hallmark stamp and grams of pure gold.
How to use the Gold Karat Purity Calculator
- Choose the karat.
- Optionally enter the item’s weight in grams.
- Read the purity and pure gold content.
How it works
Karat measures purity in parts per 24: purity = karat ÷ 24. 18K is 18/24 = 75% gold, stamped 750. The rest is alloy metals — copper, silver, zinc or palladium — that add hardness and color (rose, white or yellow gold). 24K is pure (99.9%) but soft, so most jewelry is 14K–22K.
Popular gold karat conversions
Gold purity chart
| Karat | Purity | Stamp |
|---|---|---|
| 24K | 99.9% | 999 |
| 22K | 91.7% | 916 |
| 21K | 87.5% | 875 |
| 18K | 75.0% | 750 |
| 14K | 58.3% | 585 |
| 10K | 41.7% | 417 |
| 9K | 37.5% | 375 |
Frequently asked questions
How pure is 18K gold?
75% gold.
What does 916 mean on gold?
22K gold — 91.6% pure.
Is 14K gold real gold?
Yes — 58.3% gold alloyed with other metals for strength.
How much pure gold is in a 10 g 22K chain?
About 9.17 g.
How do I test gold purity at home?
Look for a karat or fineness stamp; acid test kits and electronic testers are more reliable, and a jeweler can test with XRF.