Gold karat converter
Every karat is a share of pure gold in twenty-fourths: 21K is 21 parts in 24, 18K is 18 parts. Any weight can therefore be converted from one karat to another with one rule: multiply the weight by the original karat and divide by the target karat. Twenty-one grams of 21K hold 18.375 g of pure gold, the same as 18.375 g of 24K, about 20 g of 22K or 24.5 g of 18K. The conversion helps when adding up jewellery in several karats for zakat, when comparing a bar with a piece, or when trading a piece for one in a different karat. The calculator gives the equivalent weight, the pure gold in the piece and its current value in the currency of the Gulf country you choose. It is also handy for expats whose family jewellery is 22K from India and who are now quoted 21K prices in Saudi Arabia.
Equivalent weight in 24K
18.375 g
Same amount of pure gold
| Pure gold in the piece | 18.375 g |
| Value at today’s price | SAR 9,182 |
Checked by Radif Partners · How we calculate · Editorial policy
The one rule
Equivalent weight = weight × original karat ÷ target karat. The rule holds because every karat in Gulf markets is priced as a share of the 24K price, and the value comes from the ounce price we fetch from gold-api.com, divided by the troy ounce weight and multiplied by the exchange rate, for example 3.75 riyals per dollar per the Saudi Central Bank.
When you need it
Adding up a family’s jewellery for zakat, since the nisab is measured in pure gold, which the zakat calculator does. Estimating what a shop will give for an 18K piece if you want a 21K one in exchange. Comparing a 24K bar with a plain 22K piece holding the same pure gold. In each case the right sum starts from the pure gold, not from the weight on the scale.
Limits of the conversion
The conversion covers gold only. It ignores stones, making charges and VAT. For a set piece the gold weight must be known separately first, or the equivalent weight comes out too high. For an actual resale figure, go to the used gold calculator.