Gold Purity Calculator
Convert gold purity between karat, percentage and fineness. Enter any one value and the calculator derives the other two using the 24 karat pure gold standard.
How to convert gold purity
- Choose whether you are entering karat, percent or fineness.
- Type the value you know, for example 18 for 18k gold.
- Read the matching purity percent and fineness, then copy the result.
Examples
18 karat gold
18 karat
75% pure, 750 fineness
Fine gold by fineness
999 fineness
23.976 karat, 99.9% pure
Frequently asked questions
How do I convert karat to percentage?
Divide the karat number by 24 and multiply by 100. For example 18 karat is 18 divided by 24 times 100, which is 75% pure gold.
What does fineness mean?
Fineness states purity in parts per thousand. 750 fineness means 750 parts gold per 1000, equal to 18 karat or 75% pure.
Why is 14k gold 58.33% and not 58%?
14 divided by 24 is 0.58333, so 14 karat is 58.33% pure and 583.33 fineness. Stamps round this to 583 for convenience.
Is 24k gold truly 100% pure?
24 karat is the standard for pure gold, but refined bullion is usually stamped 999 or 9999 fineness because trace impurities remain. This tool treats 24k as exactly 100%.
What is the purity of common gold stamps?
Typical stamps are 10k at 41.7%, 14k at 58.3%, 18k at 75%, 22k at 91.7% and 24k at 100%. Each follows the karat divided by 24 rule.
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