18k Gold Rate Calculator
How to Calculate 18k Gold Rate from 24k
Understanding gold purity is essential whether you are buying jewelry, selling scrap gold, or investing in bullion. The price of gold is universally quoted for 24k (24 Karat) gold, which represents 99.9% pure gold. However, most jewelry is made from 18k gold because pure gold is too soft to hold its shape or secure gemstones effectively.
To calculate the value of 18k gold based on the current 24k market rate, you must apply a specific mathematical formula based on the ratio of gold parts to alloy parts.
The Golden Formula
The term "Karat" refers to the parts of gold per 24 units. Therefore:
- 24k Gold: 24 parts gold out of 24 (100% or 99.9% pure).
- 18k Gold: 18 parts gold out of 24 (the remaining 6 parts are alloys like copper, silver, or zinc).
To find the 18k rate, you divide 18 by 24 to get the purity percentage, then multiply by the current 24k price.
18 ÷ 24 = 0.75 (or 75%)
18k Price = 24k Price × 0.75
Example Calculation
Let's say the current market rate for 24k gold is 6,000 per gram. You want to buy a ring weighing 5 grams made of 18k gold.
- Find the 18k Rate per gram:
6,000 × 0.75 = 4,500 per gram. - Calculate Base Value:
4,500 × 5 grams = 22,500. - Add Making Charges (if applicable):
If the jeweler charges 10% for making: 22,500 × 10% = 2,250.
Total Price: 22,500 + 2,250 = 24,750.
Gold Purity Chart
Use this reference table to quickly understand the purity percentage for different karatage levels:
| Karat (k) | Parts Gold | Purity Percentage | Common Uses |
|---|---|---|---|
| 24k | 24/24 | 99.9% | Bullion, Coins, Investments |
| 22k | 22/24 | 91.6% (916 Gold) | Traditional plain gold jewelry |
| 18k | 18/24 | 75.0% | Diamond jewelry, stone settings |
| 14k | 14/24 | 58.3% | Affordable, durable jewelry |
Why Does 18k Gold Cost Less?
18k gold costs less per gram than 24k or 22k gold because it contains less actual gold content. When you buy 1 gram of 18k gold, you are effectively buying 0.75 grams of pure gold and 0.25 grams of cheaper base metals (alloys). These alloys not only reduce the cost but also change the color (creating rose gold or white gold) and significantly increase the hardness of the metal.