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Scrap Gold Purity & Metal Value Estimate

Estimate contained pure gold and its arithmetic value using entered mass, karat or purity, and a price per mass unit.

  • Formula & worked example
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Use the result with context

Results are estimates for planning and education. Confirm rates, taxes, fees, and legal requirements with the relevant institution or a qualified professional before making a financial decision.

Formula and method

Twenty grams of 18-karat material contains 15 grams of pure gold in this model. At an entered 80 per gram of pure gold, the metal value is 1,200 before deductions.

Gold fraction = karat ÷ 24; pure gold mass = material mass × fraction; metal value = pure gold mass × matching unit price

Worked example

Enter these known values and leave the other values blank.

Gold-bearing material mass
20 g
Purity in karats
18 K
Entered price per pure-gold mass unit
80 USD / g
Gold purity fraction
75 %
Contained pure gold mass
15 g
Estimated contained-metal value
1200 USD

Assumptions and limitations

  • The entered mass excludes stones and unrelated materials, and purity is assumed uniform. Purity must be positive and no greater than 24 karats or 100%.
  • The price is supplied by you, with an explicit mass denominator. No live gold quote, dealer payout, refining loss, assay fee, premium or tax is included.
  • Troy ounces and ordinary ounces are different: one troy ounce is 31.1034768 g, while an avoirdupois ounce is 28.349523125 g. Read each selected unit independently.
  • Use consistent currencies. Optional currency conversions use the captured source rates, not live market rates.

Common questions

Will a buyer necessarily pay the displayed value?

No. This is the calculated contained-metal value at your entered price. A buyer’s offer can include assay results, recovery losses, fees and a margin.

Can I enter purity instead of karats?

Yes. Enter the purity percentage and leave karats blank. A purity of 75% corresponds to 18 karats.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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