Gold Alloy Karat Calculator for Jewelers and Scrap Gold Sellers
Calculate gold melt value by karat and weight in grams, pennyweight (DWT), or troy ounces. The only free tool that shows the complete alloy composition for yellow, white, and rose gold at every karat, displays pawn vs refiner payout ranges, and confirms FTC compliance for US gold jewelry.
A gold alloy karat calculator is the starting point for any gold-selling, gold-buying, or estate appraisal workflow in the US. It converts a gold item’s karat purity and physical weight into a melt value: the intrinsic dollar worth of the gold content alone, based on the current spot price quoted on the COMEX and benchmarked by the LBMA Gold Price, set twice daily in London at 10:30 AM and 3:00 PM. The melt value is the floor of any gold transaction. What a pawn shop, estate buyer, or refiner actually offers is a percentage of that melt value, which is why knowing the melt value before you walk in the door is the single most valuable piece of information a gold seller can have. This calculator adds two features no other free web tool provides: a complete alloy composition breakdown by color, showing exactly what metals sit alongside the gold in your piece, and an FTC compliance check confirming whether the stated karat meets the US legal minimum to be sold as gold.
From Karat Hallmark to Melt Value: How Gold Purity Sets Scrap Worth
The US Karat System and Federal Hallmarking Rules Every Gold Owner Should Know
Gold purity in the United States is measured in karats, a system that divides pure gold into 24 equal parts. A piece marked 14K contains 14 parts gold and 10 parts other metals, which translates to 58.3 percent pure gold. The three-digit fineness stamp system used internationally (for example, 585 for 14K, or 750 for 18K) expresses this as parts per thousand of pure gold, which is why 14K is sometimes stamped 585 rather than 583: manufacturers use 585 to ensure the piece meets the minimum purity requirement with a small buffer.
Under the FTC Jewelry Guides (16 CFR Part 23) and the National Stamping Act (15 U.S.C. 294 et seq.), gold jewelry sold in the United States must be at least 10 karats (41.7% pure gold) to be legally described as “gold.” Items below 10K cannot use the word “gold” in product descriptions, advertising, or labeling. The National Stamping Act also requires that karat quality marks on gold jewelry be accompanied by a manufacturer’s trademark, making the hallmark legally traceable. Common US hallmarks are: 417 (10K, 41.7% gold), 583 or 585 (14K, 58.3-58.5%), 750 (18K, 75%), 916 or 917 (22K, 91.6-91.7%), and 999 or 9999 (24K, 99.9%). Items stamped “14K GF” (gold filled), “14K RGP” (rolled gold plate), or “HGE” (heavy gold electroplate) are not solid gold and have negligible gold content for melt purposes. FTC guidance available at ftc.gov. National Stamping Act full text at uscode.house.gov.
The LBMA Gold Price, established by the London Bullion Market Association through electronic auction among 13 member banks including HSBC Bank USA, JPMorgan Chase, and Goldman Sachs, serves as the global benchmark for gold valuation. It is set twice daily at 10:30 AM and 3:00 PM London time, and the resulting price is used by refiners, jewelers, pawnbrokers, and metal dealers worldwide to determine the spot value of gold in any given transaction. COMEX gold futures, traded on the CME Group exchange in New York, trade continuously during market hours and are the basis for the real-time spot price you see on financial sites. For the most accurate melt value calculation, use the current COMEX spot price rather than the previous day’s close, as gold can move several percent in a single trading session.
How to Read the Hallmark Stamp on Your Gold Piece
Every authentic solid gold piece sold in the US after 1906 should carry two stamps: the karat quality mark (10K, 14K, 18K, etc., or the equivalent fineness number) and the maker’s trademark. The quality mark appears inside rings near the shank, on bracelet clasps or tags, at the post of earrings, or on chain clasps. If a piece carries only a karat mark without a trademark, it may still be gold, but the National Stamping Act’s traceability requirement was not met, which is worth noting in any appraisal or resale context. If no stamp is visible, the piece may still contain gold, particularly for antique items predating modern stamping requirements, but testing by a certified assayer or XRF (X-ray fluorescence) instrument is necessary to verify purity before calculating melt value.
Gold Alloy Composition: What the Non-Gold Metals in Your Jewelry Actually Do
Pure 24K gold is too soft for most jewelry applications: it scratches easily, bends under minimal stress, and does not hold prongs or structural elements reliably. Alloying gold with other metals increases hardness and durability while maintaining a gold appearance. What most jewelry owners do not realize is that the choice of alloy metals is not just about durability: it fundamentally determines the color of the final piece. The same 14K karat can produce three entirely different-looking metals depending on the alloy formula used, which is why the same karat grade is available in yellow, white, and rose gold.
Yellow Gold: The Traditional Copper and Silver Formula
Yellow gold alloys use silver and copper as the primary alloying metals. The proportions are calibrated to maintain the warm gold tone while adding durability. At 14K yellow (58.3% gold), the remaining 41.7% is typically approximately 29% silver and 12.7% copper. The silver prevents the copper from shifting the color too far toward red-orange, and the combined effect preserves the traditional yellow gold appearance. At 18K yellow (75% gold), the alloy is simpler: approximately 12.5% silver and 12.5% copper, with more gold dominating the color result. This is why 18K yellow has a noticeably richer, more buttery yellow tone compared to 14K: there is simply more gold to see.
White Gold: Nickel or Palladium for a Platinum-Like Appearance
White gold gets its silvery appearance from alloy metals that suppress gold’s natural yellow color. In the US, 14K white gold typically contains nickel as the primary whitening agent, with a standard formula of approximately 58.3% gold, 16.7% silver, 12% copper, and 13% nickel. Nickel is highly effective at whitening gold and is cost-efficient, but it is a common allergen: an estimated 10 to 15 percent of the US population has nickel sensitivity, which is why many people experience skin reactions to white gold jewelry in prolonged contact. Higher-end 18K white gold often uses palladium (a platinum group metal) as the whitening agent instead of nickel, with a formula of 75% gold and 25% palladium. Palladium-alloy white gold is hypoallergenic and does not require rhodium plating to achieve a bright white finish, but it is more expensive than nickel-alloy white gold. Most US white gold jewelry receives a rhodium plating over the nickel-alloy base to improve brightness and reduce nickel skin contact, which eventually wears off and requires replating every one to three years.
Rose Gold: High Copper for a Warm Pink Tone
Rose gold achieves its characteristic pink-to-red warmth through a high copper content. At 14K rose gold (the most common rose gold in US jewelry), the formula is approximately 58.3% gold, 9% silver, and 32.7% copper. The high copper content produces the distinctive rosy hue and also makes 14K rose gold slightly more durable than 14K yellow or white gold, since copper is harder than silver. At 18K rose gold (75% gold, 4.5% silver, 20.5% copper), the color is slightly softer and less intensely pink than 14K rose, because there is more gold dominating the mix. Rose gold does not require rhodium plating and its color does not fade over time, which is why it has become increasingly popular in the US market since approximately 2015. An important note for sellers: the alloy composition of rose gold does not affect its melt value calculation. All melt calculations are based on the gold content alone (the purity fraction times the weight), and the copper and silver components have negligible effect on the total value at current gold prices.
| Karat / Color | Gold % | Silver % | Copper % | Other Metals | US Hallmark |
|---|---|---|---|---|---|
| 10K Yellow | 41.7% | 31.9% | 26.4% | None | 417 |
| 10K White | 41.7% | 10.0% | 10.6% | Ni 32.1%, Zn 5.6% | 417 |
| 10K Rose | 41.7% | 3.0% | 55.3% | None | 417 |
| 14K Yellow | 58.3% | 29.0% | 12.7% | None | 585 |
| 14K White | 58.3% | 16.7% | 12.0% | Ni 13.0% | 585 |
| 14K Rose | 58.3% | 9.0% | 32.7% | None | 585 |
| 18K Yellow | 75.0% | 12.5% | 12.5% | None | 750 |
| 18K White | 75.0% | None | None | Pd 25.0% | 750 |
| 18K Rose | 75.0% | 4.5% | 20.5% | None | 750 |
| 22K Yellow | 91.6% | 5.0% | 3.4% | None | 916 |
| 24K Yellow | 99.9% | None | None | None | 999 |
Three Real US Gold Transactions: Pawn, Refiner, and Estate Buyer
Miami’s Coral Gables and Little Havana jewelry corridors are significant US gold transaction markets, with substantial volume of 18K and 22K pieces imported from Latin American and Caribbean markets. A seller brings in an 18K yellow gold necklace (750 stamp) weighing 28.5 grams. Spot gold is $3,200 per troy ounce.
A jeweler on LA’s Hill Street jewelry district brings a lot of 14K rose gold scrap from bench filings and broken pieces: 47.2 grams total. The bench assayer confirms 14K (585 stamp). Spot gold is $3,200 per troy ounce.
A Dallas estate attorney sends a mixed gold lot to an auction house appraiser: one 10K yellow ring (4.8 g), one 14K white gold bracelet with 585 stamp (9.1 g), and one unmarked yellow piece that XRF testing confirms as 18K (6.3 g). Spot gold is $3,200 per troy ounce.
Six Expert Tips for Getting the Best Gold Value When You Sell
Know Your Melt Value Before Any Conversation With a Buyer
The single most valuable thing you can do before selling gold is calculate the melt value yourself, at the current spot price, using accurate weight measurements. This calculator gives you a floor: no legitimate buyer should offer less than 60 percent of melt value for solid gold, and refiners typically offer 85 to 95 percent. If a buyer offers you less than 55 percent of melt, walk away. Print the PDF this calculator generates and bring it to any gold buyer meeting. Buyers who know you have done your homework will typically offer closer to fair market value rather than starting with a lowball offer.
Use Pennyweight (DWT) for Trade Conversations With Jewelers and Pawn Shops
American jewelers, pawnbrokers, and estate buyers typically quote gold by the pennyweight (DWT), not by the gram. One troy ounce equals exactly 20 pennyweights, and one pennyweight equals 1.55517 grams. When a pawn shop quotes you a price per DWT, multiply by 20 to get the price per troy ounce, then divide by the karat purity fraction to get the effective spot-price equivalent they are using. This tells you immediately whether their offer is competitive. For example, if a pawn shop offers $130 per DWT for 14K gold and current spot is $3,200/ozt, their effective rate is $130 x 20 = $2,600/ozt effective, divided by 0.583 purity = $4,459 implied spot. Since actual spot is $3,200, they are effectively paying 72.2% of melt, which is in the normal pawn range of 60 to 75 percent.
Weigh Your Gold Before Arriving to Prevent Scale Manipulation
A postal or kitchen scale that reads in grams is sufficient for pre-verification of weight. Many pawn shops use scales calibrated to read slightly light, which reduces their stated offer. If the buyer’s scale reads significantly different from yours for the same piece, ask for the scale to be recalibrated in front of you or request a second weighing. A more reliable approach is to visit multiple buyers with the same piece, record their stated weight and offer, and compare. Under the Fair Trade Practices rules in most US states, using a manipulated scale in a commercial transaction is fraudulent, and significantly inconsistent scale readings from different buyers should be reported to your state’s weights and measures bureau.
Understand the Difference Between Gold Filled, Gold Plated, and Solid Gold
The terms “solid gold,” “gold filled,” and “gold plated” describe fundamentally different products with vastly different scrap values. Solid gold (10K through 24K) contains gold throughout the entire piece, and melt value calculations apply to all of it. Gold filled (stamped “GF,” “Gold Filled,” or fraction like “1/20 14K GF”) must be at least 1/20th gold by weight under US FTC rules, but the base metal under the gold layer is typically brass or copper. Gold filled jewelry has some gold recovery value (the gold layer can be refined), but significantly less per gram than solid gold. Gold plated (GP, HGE, or RGP) has an extremely thin gold layer electrolytically applied: typically 0.5 to 2.5 microns, containing negligible gold by weight. Gold plated items have essentially no melt value for private sellers, as the gold recovery cost exceeds the value. This calculator is designed for solid gold pieces only.
Time Your Sale Around Spot Price Peaks When Possible
Gold spot prices are quoted in US dollars and move continuously during COMEX trading hours (8:20 AM to 5:00 PM ET). Gold and the US dollar have a strong inverse relationship: when the dollar weakens (often during inflation, Federal Reserve rate cuts, or geopolitical uncertainty), gold prices typically rise. Gold reached a new all-time high in September 2024 at $2,685/ozt following the Federal Reserve’s 50-basis-point rate cut, then continued climbing. Gold’s longer-term trend from early 2025 to mid-2026 saw prices trade significantly above $3,000/ozt for extended periods. For non-urgent sellers, monitoring the gold price for 30 to 60 days before selling and choosing a peak day within that window can meaningfully increase the payout, since the spot price directly multiplies your melt value dollar for dollar. A $200 swing in spot price on a 30-gram 14K piece changes the melt value by approximately $114.
Separate High-Craftsmanship and Branded Pieces From Scrap Before Selling
Not every gold piece should be sold as scrap. Jewelry from recognized brands (Tiffany, Cartier, Van Cleef), pieces with significant gemstones, antique and estate pieces with historical value, and gold coins or bars from recognized mints (US Mint, Perth Mint, Credit Suisse) typically carry premiums above melt value that disappear the moment the piece is melted. For branded pieces, the retail resale price (through consignment, auction, or direct sale) may be 30 to 150 percent above melt value. For US gold coins such as the American Gold Eagle (22K, 91.7% gold) or American Gold Buffalo (24K, 99.99% pure), the numismatic market or bullion dealer premiums above spot are consistently significant. Always have a certified appraiser assess any non-standard gold piece before choosing the melt route.
According to the United States Geological Survey (USGS) Mineral Commodity Summaries, US gold mine production in recent years has been approximately 170 to 200 metric tonnes per year, with Nevada producing the majority of domestic output. The United States does not produce enough gold domestically to meet its consumption needs and is a net importer of gold for jewelry manufacturing. The US is the world’s largest consumer of polished gold jewelry and accounts for approximately 25% of global retail gold jewelry demand by value. US secondary production (recycled gold from scrap jewelry, dental gold, electronics, and industrial sources) has grown significantly as gold prices have remained elevated, with scrap recovery estimated at over 130 metric tonnes in recent years per USGS data. The USGS gold statistics and information page is available at usgs.gov/gold-statistics.
Gold Karat Quick Reference: US Hallmarks, Purity, and Melt Value per Gram
| Karat | Fineness / US Stamp | Gold Purity | Value/g at $3,000/ozt | Value/g at $3,500/ozt | US Legal? | Common Use |
|---|---|---|---|---|---|---|
| 8K | 333 | 33.3% | $32.12 | $37.47 | No (below 10K) | Germany, some European markets |
| 9K | 375 | 37.5% | $36.16 | $42.19 | No (below 10K) | UK, Australia, Ireland |
| 10K | 417 | 41.7% | $40.22 | $46.92 | Yes (US minimum) | Most affordable US gold jewelry |
| 12K | 500 | 50.0% | $48.23 | $56.27 | Yes | Uncommon; some vintage US pieces |
| 14K | 585 | 58.3% | $56.22 | $65.59 | Yes (most common) | US engagement rings, everyday jewelry |
| 18K | 750 | 75.0% | $72.34 | $84.40 | Yes | European fine jewelry, luxury watches |
| 22K | 916/917 | 91.6% | $88.34 | $103.07 | Yes | Indian bridal, American Gold Eagle coins |
| 24K | 999/9999 | 99.9% | $96.37 | $112.43 | Yes | Bullion bars, some Asian jewelry |
Value per gram = (spot price / 31.1035) x karat purity fraction. Based on example spot prices of $3,000 and $3,500 per troy ounce. Use the calculator above with today’s spot price for the current value. Prices are melt value only and do not include making charges, premiums, or numismatic value.
Your Gold Karat Calculator Questions Answered
Accuracy, Limitations, and Editorial Transparency
Melt value calculations use the formula: fine_gold_ozt x gold_spot_price, where fine_gold_ozt equals total_weight_grams x karat_purity / 31.1035. Karat purity fractions: 10K=41.7%, 12K=50.0%, 14K=58.3%, 18K=75.0%, 22K=91.6%, 24K=99.9%. Alloy compositions are representative industry-standard formulas and may vary by manufacturer and country. Actual gold piece composition can only be confirmed by XRF analysis or fire assay. Pawn shop and refiner payout ranges (60-75% and 85-95% of melt) are market estimates and vary significantly by buyer, location, lot size, and market conditions. This calculator does not provide live gold spot prices: always enter the current LBMA or COMEX spot price for accurate results. FTC compliance notes reference 16 CFR Part 23 as of the date of publication. National Stamping Act reference: 15 U.S.C. 294. USGS gold data: usgs.gov. LBMA pricing: lbma.org.uk. FTC Jewelry Guides: ftc.gov. This tool is not investment, legal, or financial advice. For estate and insurance appraisals, consult a certified gemologist-appraiser or AGS credentialed appraiser. Last reviewed August 2026.