Enter a pure-gold rate and metal weight
This gold price calculator uses your numbers and has no live market feed. Enter the weight of the gold alloy in grams or troy ounces, excluding stones and non-metal parts. Choose your currency and enter its pure-gold rate per gram. Select the carat describing the alloy itself or use custom fineness for a stated purity such as 585 or 999.9. Do not treat the carat of a thin coating as the purity of an entire plated piece.
Follow the calculation step by step
The formula is metal weight in grams multiplied by the entered pure-gold rate per gram and the purity fraction. A carat choice uses carats divided by 24; custom fineness uses parts per 1,000. Troy-ounce weights are converted using 31.1034768 grams per troy ounce. In a hypothetical example, 5 g of 18K gold has 3.75 g of pure-gold content. At an example rate of £60 per gram of pure gold, the content estimate is £225. The £60 rate is a teaching input, not a current quotation.
Avoid adjusting for purity twice
If the rate you have already refers to 18K gold, entering it as a pure-gold rate and selecting 18K would apply the adjustment again. Use a rate whose purity and units match the tool. An ounce price also needs a correct conversion before it can be used as a per-gram input. Check the source's units instead of guessing from a number.
Know what the estimate excludes
The result is not a retail valuation, insurance appraisal or buyer offer. It excludes gemstones, workmanship, branding, tax and deductions a buyer may apply. Hollow construction does not change the formula for a known actual metal weight, but uncertain weight or purity makes the input unreliable. Copy the result with its assumptions and ask a professional to establish information you cannot identify.