Gold Karat, Purity & Weight Converter
Karat, fineness, and percentage are three ways of saying the same thing: how much of an item is actually gold. Pure gold is 24 karat, or .999+ fine, or about 100%. This converter turns any karat into its fineness and percentage, and works out the pure-gold weight inside a piece once you enter its gross weight. No spot price needed — this is about purity and weight, not dollars.
Convert karat, fineness, and weight
Purity, not value. This shows how much gold is present, not what it is worth. Stamps can be inaccurate or fraudulent — testing or assay is the only way to confirm purity.
The math is direct: fineness is karat divided by 24 (18K = 18/24 = .750), and percentage is that times 100. Pure-gold weight is the gross weight times the fineness, so a 10-gram 18K chain holds 7.5 grams of actual gold. Common marks are 24K (.999), 22K (.9167, the alloy used in the American Gold Eagle and Krugerrand), 18K, 14K, and 10K. For why bullion coins favor 22K or .9999, see our 24 karat gold coin guide and the grading guide.
Estimate only — not financial advice. This calculator runs entirely in your browser, stores nothing, sets no cookies, and makes no external calls. It does not fetch a live gold price — every result is based on the spot price and figures YOU enter, and on each coin's published gold content. Gold prices are volatile and can fall as well as rise; dealer premiums, bid/ask spreads, condition, and any numismatic value are not reflected here. Confirm every number with a reputable dealer and live market data, and consult a licensed professional before buying, selling, or making a tax decision. Editorial terms & risk disclosure.