Gold Carat (Karat) Calculator
Use this calculator to estimate purity, pure gold content, and approximate melt value based on karat, weight, and current 24K gold price per gram.
What is a gold carat calculator?
A gold carat calculator helps you quickly convert karat value into purity and estimate how much an item may be worth based on weight and market price. In jewelry, the term is usually karat (K) for purity, while carat is commonly used for gemstone weight. Many people search for “carat calculator gold,” but what they need is a karat purity and value calculator.
How karat relates to purity
Gold purity is measured out of 24 parts. That means:
- 24K = 24/24 gold = 99.9%+ pure
- 18K = 18/24 gold = 75.0% pure
- 14K = 14/24 gold = 58.5% pure
- 10K = 10/24 gold = 41.7% pure
| Karat | Purity % | Fineness Mark |
|---|---|---|
| 24K | 99.9% | 999 |
| 22K | 91.7% | 916 |
| 21K | 87.5% | 875 |
| 18K | 75.0% | 750 |
| 14K | 58.5% | 585 |
| 10K | 41.7% | 417 |
Formula used in this calculator
1) Purity
Purity = Karat ÷ 24
2) Pure gold content
Pure Gold (g) = Total Weight × Purity
3) Melt value estimate
Base Value = Pure Gold (g) × 24K Price per gram
If you include a dealer adjustment:
Adjusted Value = Base Value × (1 + Adjustment% / 100)
How to use this gold calculator correctly
- Use accurate weight in grams (remove stones if possible).
- Confirm karat stamp (10K, 14K, 18K, 22K, etc.).
- Use a fresh 24K spot price per gram from a reliable source.
- Add a realistic adjustment for buying/selling conditions.
Example calculation
Suppose you have a 14K chain weighing 20 grams, and 24K gold is $70/gram.
- Purity = 14/24 = 0.5833
- Pure gold content = 20 × 0.5833 = 11.67g
- Base melt value = 11.67 × 70 = $816.90
If a dealer applies -5%:
$816.90 × 0.95 = $775.06 estimated offer.
Important notes before buying or selling gold
Jewelry value is not the same as melt value
Designer brand, craftsmanship, rarity, and condition can increase market price beyond metal value.
Hallmark and testing matter
A stamp is helpful, but professional testing (acid, XRF, or assay) is more reliable for final transactions.
Market prices move daily
Gold pricing changes throughout the day. Always recalculate with current rates before making decisions.
FAQ
Is 24K always best?
24K is the purest, but softer. 18K and 14K are more durable for daily-wear jewelry.
Can I use this for coins and bars?
Yes, if you know the purity and weight. For coins, premiums may be significant and should be added separately.
Why does my quote differ from the calculator?
Dealers include refining cost, testing risk, overhead, and margin. Use the result as a strong estimate, not a guaranteed offer.
Final takeaway
A carat calculator for gold is a practical way to understand purity and estimate value in seconds. Enter karat, weight, and current 24K price to get a clear baseline before buying, selling, or comparing offers.