Gold Weight Calculator — Purity & Value
Enter the weight of your gold item, its karatage and the live spot price to instantly see how many grams of pure gold it contains and what that gold is worth at market prices.
Weight unit
Karatage
USD/ozt
Market value of the pure gold content at the given spot price
- 1
Weight in grams
10 × 1 = 10 - 2
Purity fraction (karat ÷ 24)
18 ÷ 24 = 0.75 - 3
Pure gold content
10 × 0.75 = 7.5 - 4
Gold value
7.5 × (2,400 ÷ 31.1035) = 578.71
How does this calculator work?
Multiply the item's weight by (karat ÷ 24) to get pure gold grams, then multiply by (spot price ÷ 31.1035) to get the melt value. For example, 10 g of 18K gold at $2,400/ozt contains 7.5 g of pure gold worth about $580. Adjust the spot price to the live quote for an accurate result.
Formula
How this is calculated
Gold purity is expressed in karats on a 24-part scale: 24K is essentially pure gold (99.9%), 18K means 18 parts gold and 6 parts other metals (75% purity), and so on. The purity fraction is simply karat ÷ 24, and multiplying by the total weight gives the mass of pure gold in the piece.
Gold is internationally priced in US dollars per troy ounce (1 troy oz = 31.1035 g). Dividing the spot price by 31.1035 converts it to a per-gram price. The value of the gold content is then pure-gold grams × price per gram. This is the melt value — the amount a refiner or gold buyer would pay for the metal itself, before any premium for craftsmanship or numismatic value.
The spot price changes by the second during trading hours. Use real-time prices from Kitco, Bloomberg or your broker for an accurate valuation. The default here is an approximate 2024 benchmark; adjust it to the current figure before making any financial decisions.
Frequently asked questions
Karats (K or kt) measure gold purity on a 24-part scale, where 24K is pure gold. Carats (ct) are a unit of mass used for gemstones (1 carat = 0.2 g). They are entirely different — a piece of jewellery can be described by both, e.g. an 18K gold ring set with a 0.5 ct diamond.
A troy ounce (ozt) is the standard unit for precious metals and equals 31.1035 grams — about 10% heavier than a regular avoirdupois ounce (28.35 g). Gold spot prices are always quoted per troy ounce.
No — this calculates the melt value of the gold content only, at the raw spot price. A gold buyer, pawn shop or refiner typically pays 70–90% of melt value after deducting their processing and profit margin. Jewellers may pay more if the piece has collector or antique value.
Also known as
TG we-Calculate Editorial Team. (2026). Gold Weight Calculator — Purity & Value [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/gold-weight-calculator
TG we-Calculate Editorial Team. "Gold Weight Calculator — Purity & Value." TG we-Calculate. 2026. https://we-calculate.com/calculator/gold-weight-calculator.
TG we-Calculate Editorial Team, "Gold Weight Calculator — Purity & Value," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/gold-weight-calculator
@misc{wecalculate_gold_weight_calculator, title = {Gold Weight Calculator — Purity & Value}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/gold-weight-calculator}}, year = {2026}, note = {TG we-Calculate} }
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