Gold scrap mixing: what karat will the ingot be?
Enter the weight and karat of each lot of scrap —filings, offcuts, broken pieces— and see the karat of the ingot they make together. If you need an exact karat, you also get how much alloy or fine gold to add.
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Mix your lots
One row per lot: its weight and its karat.
13.56K
16.20 g of 13.56K gold, 564.8 parts per thousand.
- Total weight
- 16.20 g
- Pure gold
- 9.15 g
How to work out the karat of a gold mix
- 1.Sort your scrap by karat and weigh each lot.
- 2.Enter each lot with its weight and karat; add as many as you need.
- 3.Read the total weight, the pure gold in it and the ingot's karat.
- 4.To hit a particular karat, choose it and see how much alloy or 24K gold to add.
How the karat of a mix is worked out
The karat of a mix is a weighted average: each lot contributes its pure gold, its weight times its karat over 24. Add up the pure gold of every lot, divide by the total weight and multiply by 24.
Example: 5 g of 10K and 8 g of 14K. Pure gold: 5 × 10 ÷ 24 + 8 × 14 ÷ 24 = 6.75 g. Karat: 6.75 ÷ 13 × 24 = 12.46K.
Melting lots of different karats without working it out leaves an ingot of unknown fineness, and selling or working gold below its stamp is a real problem. Melt, stir well with borax and, where possible, check with a touchstone or an assay.
Dirty scrap —with solder, stones or polishing residue— loses weight in the melt. To estimate that loss, use the metal loss calculator.
Frequently asked questions
What karat do I get mixing 10K and 14K gold?
It depends on how much of each. At equal weights you get 12K; with more 14K it moves towards 14K. The calculator takes the average weighted by weight.
Can I mix yellow and white gold?
The karat works out the same, but the color comes out uneven and nickel white-gold alloys can make the metal brittle. Melt each color on its own.
How do I get exactly 14K from my scrap?
Enter your lots and choose 14K as the target. If your mix comes out higher, you get how much alloy to add; if lower, how much fine gold.
Does it work for bench filings?
Yes, as long as you know their karat. Filings carry dust and abrasive, so clean them with a magnet and a flame before weighing, or allow for the loss.