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Gold Karat Calculator: Raise or lower the purity of your gold

Instantly calculate what metals you'll need to raise or lower the purity of gold in your own studio. We've included: 9k gold, 10k gold, 14k gold, 18k gold, 22k gold, 24k gold, and yellow gold alloy mix*.
Karatage is an indication of gold content. The gold-quality system consists of 24 parts, or karats. Pure gold is called 24 karat (marked as 24k, 24kt, or 999). That means that 24 out of 24 parts of the metal are pure gold: 99.9% pure gold.

You can alter the karatage of gold by adding other metals. To increase a gold's karat, you would add pure fine gold. To lower a gold's karat, you would add alloy mix*.

Usually altering a gold's karat would require all sorts of equations, but we've done the math for you! Just plug your information into this calculator to get started.

Increasing or Decreasing Karat of Gold
Let's say you have 5 grams of 18-karat yellow gold, and you'd like to turn that into 14-karat yellow gold. What metal would you need to mix with your 18-karat gold, and how many grams would you need of this metal? How many grams of 14-karat gold would you end up with?

Use this quick calculator to find out in a flash!
I have gram(s) of gold.
I would like to change that to .
* The "alloy mix" in this calculator is for making yellow gold only.
We recommend making up gold alloy mix on its own as sheet, wire, or casting grain. Then use portions of that mix as a single metal when changing the karat of gold.

To find out the exact proportions of the metals in the gold alloy mix, use our Alloy Calculators.
For More Information
Learn how to make your own alloys, including melting temperatures and the order in which you should mix metals, read "Transform Scraps or Casting Grain into Your Own Alloys" by Art Jewelry magazine Associate Editor Addie Kidd. The article's in the May 2009 issue, on page 34.

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