How it works
The precious-metals calculator turns the gross weight of a piece of gold, silver, platinum or palladium into three values every buyer and seller care about most:
- Melt value — the pure-metal value at the current spot price, before any dealer margin
- Buy price — what a dealer typically charges you (spot + buy spread)
- Sell price — what a dealer typically pays you (spot − sell spread)
The calculator supports the three ways people usually describe a piece:
- Hallmark / stamped fineness (333 / 585 / 750 / 900 / 999 ‰, i.e. 8K / 14K / 18K / 21.6K / 24K)
- Karat (24K scale, exact: 24 × promille ÷ 1000)
- Promille (0–1000 ‰, the European alloy stamp)
Formulas
The math is straightforward once everything is expressed in grams of pure metal:
Example
A 100 g 18K gold bracelet at a spot price of €70/gram with a 5% buy and 5% sell spread.
- Fineness: 18 K = 750 ‰
- Fine weight: 100 g × 750 ÷ 1000 = 75 g pure gold
- Melt value: 75 g × €70 = €5,250.00
- Buy price (dealer → you): 5,250 × 1.05 = €5,512.50
- Sell price (you → dealer): 5,250 × 0.95 = €4,987.50
- Dealer margin: 5,512.50 − 4,987.50 = €525.00 (10 %)
Notes and assumptions
- **Troy ounce (oz t) is the world-standard precious-metals ounce, ≈ 31.1034768 g (exactly), not the avoirdupois ounce of ≈ 28.35 g used for food and postage. The calculator always uses the troy ounce.
- **999 ‰ is 99.9 % pure (investment-grade bullion). 24 K is treated as 999 ‰; mathematically 24 K = 1000 ‰, but in practice no commercial bar is 100.0 % pure, so the calculator caps hallmark 24 K-equivalent at 999 ‰.
- Spreads vary widely by metal, product and region and change constantly. Typical retail spreads on small bars and coins often range from 2 % to 15 %; use the numbers your dealer actually quotes you, not averages from the calculator's defaults.
- Taxes and duties are not included — in the calculator's output. In many jurisdictions investment-grade gold is VAT-exempt while silver, platinum and palladium are taxed; scrap jewelry is almost always taxable.
- Calculations use exact 40-digit decimal arithmetic; rounded only at display time.
Frequently asked questions
Why is a "24 K" piece not 1000 ‰?
Pure 24-carat gold is too soft for daily wear, so even "24 K" jewelry and commercial bars are almost always 999 or 999.9 fine. For consistency we treat 24 K as 999 ‰ (investment fine.
I have a price per ounce — do I have to convert it?
No — just switch the price field to "Troy ounce mode and enter it directly. The calculator converts it internally to price per gram for the fine-weight math.
Why is the sell price always lower than the buy price?
The difference (the dealer spread pays refining, fabrication, storage, insurance and the dealer's profit margin. Liquid, spread on larger bars is tighter; scrap jewelry has a wider spread because it has to be assayed and refined.