Mixed Karat Gold Calculator
Live gold price: $4049.50 / troy oz · updated
Why mixed gold needs rows, not one average karat
A jewelry box rarely contains one purity. A 10K class ring, 14K chain, 18K setting, and 22K coin cannot be valued accurately by adding their weights and selecting a convenient middle karat. Each row needs its own weight, unit, and purity; the calculator converts every row to grams, subtracts declared non-gold weight, calculates pure gold, and then totals the lot.
This preserves an audit trail. If your number differs from a buyer's, you can compare one item at a time instead of debating a mystery average. For a single homogeneous item, the main scrap gold calculator is faster. Use this page when two or more pieces have different stamps, test results, units, or stone deductions. Keeping rows separate also preserves the gold evidence a second buyer needs: original gold weight, tested purity, and the exact non-gold deduction applied to each piece.
Sort by stamp, then verify what the stamp means
Group 10K with 417 marks, 14K with 583 or 585, 18K with 750, 22K with 916 or 917, and 24K with 999 or 9999. These are common mappings, but the suffix matters: GP, GEP, HGE, RGP, and GF describe plated or gold-filled products, not solid gold at the full item weight. Leave an uncertain piece out until it is tested.
Stamps are evidence, not infallible assays. Repairs, solder, clasps, and replacement parts can differ from the main object. When a buyer tests a piece at another purity, ask which method was used and record the result as its own row. Custom purity accepts a documented percentage without forcing it into the nearest karat.
Deduct stones and non-gold parts on the correct row
The non-gold field is in the same unit as that row. Enter a one-gram stone deduction on a five-gram ring, and the calculator applies purity to four grams of metal—not to the original five. This matters because subtracting all stones after the lot is blended can assign the deduction to the wrong purity.
Only enter a deduction you can support. If the stone is mounted and its weight is unknown, record the gross row and make the uncertainty explicit when comparing quotes. Do not assume every clasp or spring is base metal either; identify components, separate them if practical and safe, or let the buyer document the net metal weight.
How weighted gold purity is calculated
Pure gold weight for each row equals net metal grams × purity. Add those pure-gold weights, then divide by total net metal grams to get weighted purity. A weighted result of 63.1% does not mean the lot is “15.1K jewelry”; it is only a mathematical summary of several separate items and should not replace the original rows.
Melt value is total pure-gold grams × spot price per gram. The tool converts the quoted troy-ounce price using 31.1034768 grams per troy ounce. If you want to inspect each karat's one-gram value first, use the gold price per gram table.
Worked example: 14K plus 18K with a stone deduction
Take 10 grams of 14K gold and a five-gram 18K ring containing an estimated one gram of non-gold material. The first row holds 10 × 14/24 = 5.833 grams of pure gold. The second row has four net metal grams at 75% purity, or three pure-gold grams. The lot therefore contains 8.833 pure-gold grams across 14 net metal grams, a weighted purity of about 63.1%.
At a $4,000-per-troy-ounce illustration, pure gold is $128.60 per gram and the combined melt value is about $1,135.99. The calculator uses the displayed price, so the dollar result moves while the weight and purity record stays the same. If a buyer offers one lump sum, enter that offer in the pawn shop gold calculator after completing this lot.
Model your own payout scenario instead of accepting a preset
A payout scenario is simply melt value × a percentage you choose. It is useful for comparing written quotes or accounting for a known contract, but the site does not supply a universal “typical” rate. Enter a percentage from an actual quote or a scenario you want to test, and the summary will show the corresponding dollars.
Keep fees separate. If one buyer offers 85% with a shipping or assay fee and another offers a lower percentage with no fee, calculate net cash for both. Percentage alone is not the decision; it is a shared language for comparing offers once every deduction is visible.
Build a gold lot sheet a buyer can verify
Number each piece or group, photograph it, record stamp or assay, weight, unit, and non-gold deduction, then keep the calculator summary with your quote notes. Use the print button to save a paper or PDF copy before you visit a buyer. A lot sheet makes missing pieces, changed weights, and blended purities easier to catch.
Do not treat the output as an appraisal. It excludes design, brand, gemstones, collectible value, taxes, and transaction costs. Its job is narrower and more useful: tell you exactly how much gold your declared rows contain and what that gold melts for at one documented price.
Frequently Asked Questions
Can different karats of gold be melted together?
They can be processed as a lot, but value each item or tested group separately first. The weighted purity is a summary, not a substitute for the row-level record.
How do I calculate the average karat of mixed gold?
Convert each row to pure-gold weight, add those amounts, and divide by total net metal weight. The calculator reports weighted purity as a percentage.
Where do I enter gemstone weight?
Enter it as non-gold weight on the same item row and in the same unit. The deduction is applied before that row's purity.
Can I mix grams, pennyweight, and ounces?
Yes. Select the unit per row; the calculator converts each amount to grams before totaling.
Does the total include buyer fees or jewelry resale value?
No. It is a metal melt calculation. Use a custom payout scenario for a known percentage and account for fees, stones, brand, and collectible value separately.