Scrap Gold Value Formula: The Math Behind Melt Value

The scrap gold value formula is the core equation used to determine the melt value of any gold item. Whether you're selling old jewelry, dental gold, or electronic scrap, this formula gives you the baseline worth before any dealer fees or refining costs are applied. It's the same calculation used by refiners, pawn shops, and online gold buyers. Understanding this formula puts you in control when negotiating a fair price.

The Scrap Gold Value Formula

The formula is straightforward:

Melt Value = Weight (troy oz) × Purity (%) × Gold Price per Troy Ounce

To use this equation, you need three pieces of information: the weight of your item in troy ounces, its purity expressed as a decimal, and the current market price of gold per troy ounce. The result is the value of the pure gold content — also called fine gold — in your scrap.

Breaking Down Each Variable

Weight (troy oz): Gold is weighed in troy ounces, not standard ounces. One troy ounce equals 31.1035 grams, about 10% heavier than a regular ounce. Most household scales measure in grams or standard ounces, so you'll need to convert. The calculator on this site handles that conversion for you.

Purity: Gold purity is often stamped as karats (e.g., 14K, 18K, 24K). To use the formula, convert karats to a decimal: divide the karat number by 24. For example, 18K gold is 18/24 = 0.750 (75% pure). Pure 24K gold has a purity of 1.0. The formula uses this decimal to isolate the gold content from alloys.

Gold Price per Troy Ounce: This is the spot price of gold, typically quoted in U.S. dollars per troy ounce. Prices fluctuate constantly based on global markets. You can find the live price on financial news sites or use the built-in price in our Scrap Gold Calculator.

Why the Formula Works

The formula relies on a simple principle: the value of scrap gold equals the value of the gold it contains. All other materials (copper, silver, nickel) are considered worthless for melt purposes. By multiplying weight by purity, you get the weight of pure gold in the item. Multiplying that by the current price gives its melt value.

Units check: Weight (troy oz) × Purity (unitless) × Price ($/troy oz) = Value ($). The units cancel to dollars. The same logic applies if you convert to grams: just use price per gram instead of per troy ounce.

Historical Note

The use of troy ounces dates back to the Middle Ages, originating in the French town of Troyes. The troy system became the standard for precious metals because of its consistency across international trade. Even today, all gold markets quote prices per troy ounce, making this formula universal.

Practical Implications for Sellers

While the formula gives the melt value, you'll rarely receive that full amount when selling. Most dealers pay between 70% to 95% of melt value, depending on the item's condition, purity, and quantity. This is called the dealer payout percentage. For example, if your scrap's melt value is $1,000 and the dealer pays 80%, you'd get $800. Our calculator includes this option so you can see realistic estimates. For a deeper look at typical payout ranges, visit our page on Scrap Gold Value Ranges.

The formula also highlights why purity matters more than total weight. A heavy 10K ring may have less gold value than a lighter 18K necklace. Always check for hallmarks or get the gold tested before estimating. For detailed instructions on measuring and calculating, see How to Calculate Scrap Gold Value.

Weight Conversion Tables

Here are common conversions to troy ounces:

Edge Cases and Special Situations

The basic formula works for most scrap gold, but some items require extra care:

Mixed or Unknown Purity

Items without hallmarks (e.g., some vintage jewelry or dental gold) need professional testing. Refiners use acid tests or X-ray fluorescence to determine purity. Until you know the exact karat, the formula can only give a rough guess. For more on different gold sources, see Scrap Gold Value by Source.

Gold-Filled or Plated Items

Gold-filled items have a thin layer of gold bonded to a base metal. They contain very little gold (often 5% or less of the total weight). The formula still works — just use the actual gold content weight. Plated items have even less gold; often the plating is too thin to recover economically.

Dental Gold

Dental crowns and bridges are typically 16K–18K but may contain metal alloys like palladium or platinum that add value beyond pure gold. A standard refiner would assay the item and pay based on all precious metals present.

Electronic Scrap

Gold in electronics (pins, connectors) is usually very thin and mixed with other metals. The weight of the whole component isn't the gold weight — you'd need to know the gold content per part, often expressed in grams per ton of scrap. For most individuals, it's better to sell bulk electronic scrap to specialized recyclers.

In all cases, the formula remains your foundation. Once you have accurate weight, purity, and price, you can compute a reliable melt value. For answers to common questions about selling scrap gold, check our Scrap Gold Value FAQ.