Instant 18k Gold Value Calculator
Formula used: 18k price/gram = (spot per ounce ÷ 31.1034768) × 0.75 × (1 + premium%).
What this calculator does
This tool estimates the 18k gold price per gram from the live market price of pure gold (24k). Because 18k gold is 75% pure, its melt value is lower than 24k. The calculator helps you quickly estimate:
- 18k melt value per gram
- Adjusted 18k price per gram with premium or discount
- Total estimated value for your jewelry weight
How 18k gold price per gram is calculated
1) Convert spot price from ounce to gram
International gold prices are quoted per troy ounce. One troy ounce equals 31.1034768 grams. So first, we convert 24k gold from ounce pricing to per-gram pricing.
2) Apply 18k purity (75%)
18k gold means 18 parts gold out of 24 total parts, which equals 75% purity. We multiply the 24k per-gram value by 0.75 to get base 18k melt value.
3) Add dealer premium or discount
Retail and resale markets often differ from melt value. Making charges, brand markup, local taxes, and buyback spreads can create a premium (or discount). Use the premium field to model those differences.
4) Multiply by total grams
Finally, multiply the adjusted 18k price per gram by your item weight to estimate total value. This is useful for rings, chains, bangles, scrap gold, and custom jewelry quotes.
Quick example
Suppose spot gold is $2,400/oz, FX is 1.00, premium is 5%, and jewelry weight is 10g:
- 24k per gram = 2400 ÷ 31.1034768 = $77.16
- 18k melt per gram = 77.16 × 0.75 = $57.87
- Adjusted 18k per gram = 57.87 × 1.05 = $60.76
- Total for 10g = 60.76 × 10 = $607.60
Why 18k gold costs less than 24k
Pure gold (24k) is soft. 18k gold mixes gold with other metals for durability and color tone. Since only 75% of 18k is pure gold content, its raw metal value is lower than 24k. However, final jewelry price may still be high because of craftsmanship, design, and branding.
Key factors that impact your final price
- Global gold spot price: moves daily with macroeconomic conditions.
- Currency exchange rate: local pricing changes as FX changes.
- Premiums and margins: retail markup, design complexity, and merchant policy.
- Hallmark purity: verify 18k stamp (750) to confirm gold content.
- Weight accuracy: small scale differences can materially change value.
Tips for buyers and sellers
If you are buying 18k jewelry
- Ask for gold purity certification or hallmark details.
- Compare price-per-gram across multiple sellers.
- Separate metal value from making charges in your quote.
If you are selling 18k gold
- Get at least 2–3 buyback offers.
- Ask whether deductions include assay/testing fees.
- Use this calculator to estimate fair negotiation range before visiting buyers.
Frequently asked questions
Is 18k gold always exactly 75%?
Legally, 18k is defined as 75% pure gold, though tiny manufacturing tolerances may apply. Hallmark “750” is the common indicator.
Does this calculator include gemstones?
No. It estimates metal value only. If your item has stones, craftsmanship value can be significant and should be appraised separately.
Can I use this for rose gold or white gold?
Yes. If purity is 18k, the gold-content math is the same. Color differences come from alloy metals, not from more gold.
Bottom line
The fastest way to estimate 18k gold value is: convert spot to gram, apply 75% purity, then adjust for premium. Use the calculator above whenever you compare quotes, evaluate buyback offers, or check if a jewelry price is reasonable.