Spot18K Gold Calculator
Estimate the melt value of 18K jewelry by weight, using a gold spot quote and the karat fraction.
Gold · $3,887.60 USD/ozt · $124.99 USD/gMarket quote · Gold API · 2026-11-14 14:09 UTC
Your item
100% Melt Value
7.5 g fine gold
- Estimated buyer payout · 80%
- $749.94
- Illustrative payout range · 70–100%
- $656.19 – $937.42
18K gold price by weight
| Weight | Melt value (USD) |
|---|---|
| 1 g | $93.74 |
| 5 g | $468.71 |
| 10 g | $937.42 |
| 20 g | $1,874.84 |
| 30 g | $2,812.26 |
| 40 g | $3,749.68 |
| 50 g | $4,687.10 |
| 100 g | $9,374.19 |
How to calculate melt value
Melt value = weight in grams × purity fraction × (USD spot price per ozt ÷ 31.1034768)
At 18K purity, 10 g contains 7.5000 g of fine gold. Use 31.1034768 g per troy ounce or 1.55517384 g per pennyweight.
Estimated payout = melt value × selected payout percentage.
Gold Hallmark & Stamp Guide
| Stamp | Karat | Gold content |
|---|---|---|
| 999 | 24K | 99.9% |
| 916 | 22K | 91.6% |
| 875 | 21K | 87.5% |
| 750 | 18K | 75.0% |
| 585 | 14K | 58.5% |
| 417 | 10K | 41.7% |
| 375 | 9K / 9ct | 37.5% |
Frequently asked questions
How pure is 18K gold?
18K is 18/24 gold by weight on the nominal karat scale.
What does a 750 mark mean?
It indicates approximately 750 parts gold per thousand. Confirm the alloy if the stamp is worn or the piece is plated.
Does white 18K gold use the same formula?
Yes. Yellow, white and rose 18K use the same nominal 75% gold fraction when they are solid 18K alloys.
Why does a dealer offer less than melt value?
A buyer may deduct refining, testing, shipping or operating costs. Ask for a written net offer with the tested purity and payable weight.
Should I weigh gemstones with the gold?
Use only the weight of the gold alloy. Stones, springs and other non-gold parts can overstate the result.