A karat signifies the percentage of gold present in a piece of metal. It is 1/24 part or 4.1667% of the whole. Pure gold is 24 karats, and a product that contains 14 parts gold and ten parts other metal is 14-karat gold, or 58.33% gold.

Likewise, an item with a purity of 18 karat encompasses 18 parts gold and 6 parts other metals or alloys, or 75% gold. To convert karats to a percentage, divide the karat value by 24, then multiply the result by 100.