The Gold Purity & Karat Calculator tells you how much real gold is in a piece of jewellery. Pick the karat and enter the weight, and it shows the purity as a percentage, the pure gold content in grams, and — if you enter the day’s rate — the value of that pure gold. It’s the easiest way to understand what “22K” or “18K” actually means for your item.
It’s handy when buying, and especially when selling or exchanging old gold, since jewellers pay for the pure gold content. Everything runs in your browser and nothing is stored.
How to use the gold purity calculator
- Choose the karat of your gold — 24K, 22K, 20K, 18K, 14K, 10K, or 9K.
- Enter the weight of the piece in grams.
- Optionally enter today’s 24K gold rate to see the value of the pure gold.
- Read the purity percentage and the pure gold content.
Karat to purity chart
- 24K — 99.9% pure (hallmark 999), the purest, used for coins and bars.
- 22K — 91.6% pure (916), the most common for Indian gold jewellery.
- 18K — 75.0% pure (750), popular for diamond and Western jewellery.
- 14K — 58.5% pure (585) and 9K — 37.5% pure (375), more durable, lower gold content.
Why purity matters
Pure 24K gold is soft, so jewellery is made from an alloy — gold mixed with metals like copper and silver for strength and colour. The karat tells you the proportion of gold: 22K means 22 parts gold out of 24, which is 91.6%.
When you sell or exchange old gold, you’re paid for the pure gold content, not the total weight — so a 10 g 22K chain contains 9.16 g of gold. Knowing this helps you judge a fair price and avoid being underpaid.
Frequently Asked Questions
What is the purity of 22K gold?
22K gold is 91.6% pure, hallmarked as 916. The remaining 8.4% is other metals added for strength. So 10 g of 22K gold contains 9.16 g of pure gold.
How do I calculate pure gold content?
Multiply the weight by the purity percentage. For example, 20 g of 18K gold (75%) contains 20 × 0.75 = 15 g of pure gold. This calculator does it for any karat.
How is karat related to purity percentage?
Karat is gold parts out of 24. Purity % ≈ karat ÷ 24 × 100. Hallmark standards round these to 999 (24K), 916 (22K), 750 (18K), 585 (14K), and so on.
Which karat is best?
It depends on use. 22K suits traditional jewellery with high gold content; 18K and 14K are more durable and better for daily wear and stone settings; 24K is for investment coins and bars.