Gold purity calculator: fine gold in a bar
Fine gold content from weight and fineness, in grams and troy ounces, with the karat equivalent.
What's in an unrefined bar
Unrefined gold is part gold, part other metals. Its fineness, in parts per thousand (‰), says how much of the bar is gold. Try it with your own numbers.
The figures shown are examples (100 g at 900‰). The assay report for a real lot gives its exact weight and fineness. One troy ounce is 31.1035 grams.
How it's worked out
Fine gold = gross weight × fineness ÷ 1000. A 100 g bar at 900‰ contains 90 g of gold. The other 10 g is mostly silver, with small amounts of other metals.
Troy ounces = grams ÷ 31.1035. Gold is priced per troy ounce, which is heavier than an ordinary ounce (28.35 g).
Karat = fineness × 24 ÷ 1000. Karats are how jewelry is described; 900‰ works out at 21.6 karat. Unrefined bars are described by fineness, so the karat figure is only there to compare.
Karats and fineness
The same purity in three ways. Fineness is what an assay report states; karats are common for jewelry.
| Karat | Fineness | Gold |
|---|---|---|
| 24 k | 1,000‰ | 100% |
| 22 k | 916.7‰ | 91.7% |
| 21 k | 875.0‰ | 87.5% |
| 18 k | 750‰ | 75% |
| 14 k | 583.3‰ | 58.3% |
| 10 k | 416.7‰ | 41.7% |
| 9 k | 375.0‰ | 37.5% |
Rounded to one decimal place. Assay reports give fineness to at least one decimal place.
What the calculator doesn't tell you
It shows arithmetic, not a price. Bargold quotes each lot in writing, and the quote includes our margin.
A refinery that buys unrefined gold assays it again, pays for the gold (and sometimes silver) it measures, and deducts refining and other charges. What it pays will be less than the calculated value of the gold content.
Nothing here is investment, tax or legal advice.
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