How to Calculate the Value of Your Gold

To estimate your gold’s metal value, match the weight and purity of the item to a gold price in the same currency and unit. The result is a reference value. It is different from a shop price, an insurance valuation or the cash a buyer will offer.

Start with GoldRates’ current reference prices, then follow the steps below. Record the date of your calculation and use the latest available rate when comparing a real offer.

1. Identify the weight you are valuing

For jewellery, use the net gold-alloy weight. This includes the gold and the metals alloyed with it, but excludes stones and unrelated materials. A necklace weighing 12g with 2g of non-gold components has 10g of gold alloy to value, provided those weights have been established accurately.

Do not remove stones or dismantle an item just to estimate its value. Ask a qualified jeweller to confirm the relevant weight if the invoice does not separate it. If different components have different purities, value them separately where reliable measurements are available.

2. Understand the purity mark

Karats describe gold as parts out of 24. Fineness describes parts out of 1,000. For example, 18K is 18 ÷ 24 = 75% gold, while a fineness mark of 750 also indicates 75%.

Commercial fineness and nominal karat ratios can differ slightly. For instance, 22 ÷ 24 is approximately 91.6667%, whereas 916 means 91.6%. Use the verified fineness when precision matters, rather than treating the two numbers as identical.

Read our karat and fineness guide for more detail. The UK government’s hallmarking guidance explains the UK system. Marking rules differ by country, and a stamp alone is not a substitute for verification.

3. Choose the calculation that matches your rate

If the rate already matches the item’s purity:
Reference value = gold-alloy weight × price per gram for that purity.

For example, 10g of 18K gold at a hypothetical 18K reference rate of US$75 per gram gives US$750. Do not multiply by 0.75 again. The rate already accounts for purity.

If the rate is for 100% fine gold:
Reference value = gold-alloy weight × fineness as a decimal × fine-gold price per gram.

At a hypothetical fine-gold price of US$100 per gram, the same item gives 10 × 0.750 × US$100 = US$750. Both methods agree because the assumed 18K rate is US$100 × 0.750.

Worked examples for different purities

This table uses an assumed price of US$100 per gram of 100% fine gold. These are teaching examples, not current market quotes. All weights exclude stones and other non-gold components.

What if your reference rate represents 999 gold?

Check the price basis before treating a rate labelled 24K as a price for 100% fine gold. If it specifically represents one gram of 999 gold, the precise conversion is:

Reference value = item weight × (item fineness ÷ reference fineness) × reference price per gram.

If 999 gold is hypothetically US$100 per gram, 10g of 750 gold is 10 × (0.750 ÷ 0.999) × US$100 = approximately US$750.75. This small difference comes from the price basis. Use the provider’s stated convention, and avoid implying that an approximate purity rate is an exact assay valuation.

Match the weight unit and currency

The US National Institute of Standards and Technology conversion table gives one troy ounce as 31.1034768 grams. Divide a price per troy ounce by that number to obtain a price per gram on the same purity basis. A regular household ounce is a different unit.

Keep the currency consistent throughout. If conversion is needed, check the direction of the exchange rate and any transaction fees. Our currency-conversion guide explains the process.

Turn a reference value into a useful comparison

• Buying jewellery: Request an itemised price. Our making-charges guide explains the costs added to metal value.
• Selling: Compare the final payout after fees. Use our gold-selling checklist before agreeing to testing or payment terms.
• Special pieces: Obtain a specialist opinion if a coin or jewellery item may have collectible value. Metal arithmetic does not measure rarity or craftsmanship.
• Tracking holdings: My Gold provides a USD reference-value tracker. Its value estimate is not a guaranteed resale amount, and saved holdings remain in the browser used to enter them.

Keep a record of the measured weight, verified purity, rate source, price basis and calculation date. Those details make your estimate reproducible and help you understand why a dealer’s final quote differs.