What is a karat?
A karat (K) measures gold purity in 24ths. Pure gold is 24K. A piece marked 18K contains 18 parts gold and 6 parts other metals, which is 75% gold.
Purity table
24K is about 99.9% gold. 22K is 91.67%. 21K is 87.5%. 18K is 75%. 14K is 58.5%. 10K is 41.7%.
Why lower karats exist
Pure gold is soft. Alloying with copper, silver or other metals makes jewellery harder and changes its colour, and lowers the cost.
How to estimate the value
Multiply the price per gram of pure gold by the purity of your piece and by its weight in grams. Example: for an 18K piece, use 75% of the 24K price per gram. Real offers from dealers are lower because they deduct margin, refining costs and sometimes the value of stones.
Use the calculator
Our calculator converts weight, karat and currency using the live price. Country pages show the 24K to 10K price per gram in local currency.
Educational content, not investment advice.