Gold is quoted per troy ounce, but jewelry and scrap are usually weighed in grams. Convert by dividing spot price per troy ounce by 31.1035.
24K price per gram = spot price per troy ounce ÷ 31.1035karat price per gram = 24K price per gram × purity
Check the live Gold Price Per Gram
Why gold uses troy ounces
1 troy ounce = 31.1035 g (heavier than a regular ounce). If spot is $1,900/oz: 1900 ÷ 31.1035 = $61.09/g for pure gold.
Formula by karat
| Karat | Purity | Formula |
|---|---|---|
| 10K | 41.7% | 24K price × 0.417 |
| 14K | 58.5% | 24K price × 0.585 |
| 18K | 75.0% | 24K price × 0.750 |
| 22K | 91.7% | 24K price × 0.917 |
| 24K | 99.9% | 24K price × 0.999 |
Worked example
Spot = $1,880/oz. Then 24K/g = 1880 ÷ 31.1035 = $60.44. 18K/g = $60.44 × 0.750 = $45.33. 14K/g = $60.44 × 0.585 = $35.36.
Weight conversion quick reference
| Unit | Grams | How to use it |
|---|---|---|
| 1 gram | 1.000 g | Standard jewelry quoting in many markets |
| 1 DWT | 1.5552 g | Common in scrap and refinery trade terms |
| 1 troy ounce | 31.1035 g | Global bullion and spot benchmark |
| 1 tola | 11.6638 g | Traditional quoting in South Asia and Gulf contexts |
Common calculation mistakes
- Using regular ounce instead of troy ounce (this breaks the whole conversion).
- Applying 24K per-gram directly to 14K/18K jewelry without purity adjustment.
- Mixing currencies mid-calculation without updating FX assumptions.
- Rounding too early before multiplying by purity and weight.
- Treating per-gram quote as final buyer offer without payout discount.
When to use this formula vs calculator
Use manual math when you need to explain pricing logic or audit a quote line-by-line. Use the live calculator when you need fast scenario testing across currencies, payout bands, and weight units.
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FAQ
Why divide by 31.1035?
Because spot is quoted per troy ounce and a troy ounce equals 31.1035 grams.
Is 24K exactly 100% pure?
Market calculators often use 0.999 for practical pricing and hallmark consistency.
Why does my store quote differ from this number?
Store quotes include spread, assay assumptions, business margin, and sometimes embedded service costs.
Can I use the same formula for 22K?
Yes. Calculate 24K per gram first, then multiply by 0.917 for 22K.
Per-gram price vs item value
Per-gram price is only one part of item value. You still need total weight, purity, payout %, currency conversion, and net-gold assumptions.