👑 Gold Karat Converter
Turn a karat rating into its purity percentage and fineness — the two figures used to hallmark and describe gold, from a knight’s signet to a museum crown.
✨ Read the Hallmark
What does the karat tell you?
Karat measures how much of an item is gold, in parts out of 24. This converter restates that as a percentage and as fineness (parts per thousand), the number you see in a European hallmark. So 18-karat becomes 75% and 750 fine; 22-karat, the classic coin gold, becomes roughly 91.7% and 917 fine.
Knowing purity is the first step to understanding a piece — pair it with weight and a spot price to estimate melt value, and always confirm a hallmark by assay before trusting it on anything valuable.
❓ Frequently Asked Questions
What is a karat?
Karat (spelled carat outside the US, but distinct from the gemstone carat) measures the purity of gold in twenty-fourths. 24-karat is pure gold; 18-karat is 18 parts gold to 6 parts other metals, or 75%; 14-karat is 14/24, about 58.3%. The remaining parts are alloy metals that add strength and colour.
How does karat relate to fineness?
Fineness expresses purity as parts per thousand instead of parts per 24. Multiply the karat fraction by 1000: 18-karat is 750 fine (hallmarked '750'), 22-karat is about 917, and pure 24-karat is 999 or 1000. Fineness hallmarks are the European convention; karat marks are common in the US and UK.
Why isn't jewellery made of pure gold?
Pure 24-karat gold is soft and scratches and bends easily, so it wears poorly in rings and settings. Alloying it with copper, silver, palladium, or zinc hardens it and creates colours like rose and white gold. That is why most fine jewellery is 18k or 14k rather than 24k.
Is this converter enough to value an item?
It tells you purity, not price. To estimate value you also need the item's weight and the current gold spot price — pair this with a melt value calculator. And a hallmark should be confirmed by assay for anything valuable, since marks can be worn, faked, or applied to plated pieces.