Gold Karat Calculator
Turn a karat into a percent and a fineness, or go the other way. Then see how much pure gold is in the weight you have.
Karat, percent and fineness
14.00K is 58.33% gold, fineness 583.3. That is standard 14K, usually stamped 585.
1 troy oz = 31.1 g · 1 oz = 28.35 g · 1 dwt = 1.555 g
On this page
Karat ÷ 24 is the gold fraction. Multiply by 100 for a percent, or by 1,000 for a fineness. 18K is 75% and 750. 14K is 58.3%, while the stamp on the metal says 585.
Three names for one purity
Jewelers say karat. Assay offices say fineness. A chemistry textbook says percent. They are the same fact written three ways. Karat counts gold parts out of 24. Percent counts gold parts out of 100. Fineness counts gold parts out of 1,000. Divide a karat by 24 and you have the fraction. Move the decimal point and you have the others. 18 ÷ 24 is 0.75, which is 75% and fineness 750. The converter at the top edits any one of the three and fills the other two so you do not have to keep the decimal in your head.
The formula and the stamp agree for some karats and not for others. 18K, 9K, 12K and 21K land on round fineness numbers: 750, 375, 500 and 875. 14K does not. 14 ÷ 24 is 58.3%, fineness 583.3, and the mark struck into 14K jewelry is 585, which is 58.5%. 22K is 91.7% by the formula and 916 on the stamp, which is 91.6%. 24K is 100% by the formula and 999 on a bar, which is 99.9%. This site’s karat calculators price the formula, karat divided by 24. When you care about the stamp instead, type the stamp here. 585 comes back as 58.50% and 14.04K. That is the commercial mark, not a new alloy.
Weight is separate from purity. A fineness tells you the fraction. Grams tell you the amount. The weight field, with the four-unit switch, multiplies those. One pennyweight is 1.55517384 g, one troy ounce is 31.1034768 g, and one regular ounce is 28.349523125 g. Ten grams at 750 fineness is 7.5 grams of pure gold, whatever the gold price is doing. This tool stops at pure grams. The gold calculator turns pure grams into money, and it has a Custom purity field for the percent this page just gave you.
The chart from 8K to 24K
Percent and fineness in the table are karat ÷ 24. The stamp is the mark you are likely to see on the metal, which is not always that same number. Open a karat page when the row has one.
| Karat | Percent | Fineness, karat ÷ 24 | Common stamp | Calculator |
|---|---|---|---|---|
| 24K | 100% | 1,000.0 | 999 | Open calculator |
| 22K | 91.7% | 916.7 | 916 | Open calculator |
| 21K | 87.5% | 875.0 | 875 | Use custom purity |
| 18K | 75% | 750.0 | 750 | Open calculator |
| 14K | 58.3% | 583.3 | 585 | Open calculator |
| 12K | 50% | 500.0 | 500 | Use custom purity |
| 10K | 41.7% | 416.7 | 417 | Open calculator |
| 9K | 37.5% | 375.0 | 375 | Open calculator |
| 8K | 33.3% | 333.3 | 333 | Use custom purity |
8K (333) shows up on older European pieces and is below the US line for calling an item karat gold. 12K (500) is an exact half. 21K (875) is a traditional fineness in parts of the Gulf, a step under 22K. None of those three has its own page. Read the percent here, then enter it as Custom purity on the gold calculator. 9K, 10K, 14K, 18K, 22K and 24K each have a locked-karat calculator with a weight table.
Which karat is my piece?
Start with the stamp, not the color. Yellow, white and rose are choices of alloy, and a plating can imitate all three. Look inside a ring, on the clasp of a chain, on the plate of a bracelet, and between the lugs of a watch. You are hunting a karat (“14K”, “18kt”, “9ct”) or a three-digit fineness (585, 750, 375, 916, 999). A maker’s name beside the number is the company. It is not a second purity.
Britain writes 9ct where the US writes 9K. Both are 375. “Carat” on a British hallmark is gold purity. “Carat” next to a diamond is a stone weight of 0.2 grams and says nothing about the band. If both appear on one ring, the 375 or the 9ct is the gold, and the carat figure is the stone.
Some marks mean the piece is not solid gold at all. GF means gold-filled, a layer of gold bonded to base metal. A fraction such as 1/20 tells you how much of the weight that layer is. GP, GEP, HGE and RGP mean plated, a film thin enough that the karat named next to them describes the film, not the object. Pricing a plated chain as solid 14K is the error this chart cannot save you from if you ignore those letters.
No stamp means no answer yet. Color is not a test. A magnet is only a screen, because plenty of non-gold metals are not magnetic, and some gold-filled clasps have a steel spring that is. Acid tests and XRF guns are how a shop reads an unmarked piece. Watch the test. A thick plate can fool a quick acid scratch if it never reaches the metal underneath. If two stamps disagree, do not average them. Price the part you are selling, or treat the item as two items.
Once you have a number, use the chart. If it is one of the six karats with a page, open that page and type the weight. The karat there is locked, so the result cannot drift. If it is 8K, 12K, 21K, or an odd fineness such as 740 or 995, stay on this converter, read the percent, and price that percent on the gold calculator. 995 is 99.5%, which is close to 24K and is not the same number on a large bar. 999 is 99.9%. The 24K page prices 100% so that a 24K choice stays simple. Say which one you mean.
What to do with the pure-gold weight
Pure grams are the bridge between a stamp and a price. Take the item’s weight, multiply by the fraction from this page, and you have the gold a refiner can recover if the stamp is true and the scale was honest. Stones, springs, enamel, lacquer and steel pins are not in that fraction. They have to be out of the weight before you multiply. A locket weighed shut, with the photo and the glass, is a heavy way to fool yourself.
The dollar value of those pure grams is the spot price per gram times the pure grams. The spot price per gram is the troy-ounce price divided by 31.1034768. Every karat page on this site does that step and shows the time on the quote. This page leaves the price off so the conversion stays true even when the market is closed. When you want the money, you already know which calculator to open.
Selling adds one more cut. Buyers pay under melt because they test, refine and keep a margin. The pure-gold weight is what they are pricing. The percent they pay is their business, and it is estimated on the scrap gold calculator rather than here. A 750 chain and a 375 chain of the same weight do not get different payout percentages. They get different melt values, because one is three quarters gold and the other is three eighths.
Gold Karat Calculator questions
How do I convert karat to a percent?
Divide the karat by 24 and multiply by 100. 18K is 18 ÷ 24 = 75%. 14K is 14 ÷ 24 = 58.3%. 9K is 9 ÷ 24 = 37.5%. The converter on this page does that, and it also shows the fineness, which is the same purity written out of 1,000.
How do I convert a fineness number to karat?
Divide the parts-per-thousand figure by 1,000, then multiply by 24. 750 ÷ 1,000 = 0.75, and 0.75 × 24 = 18K. 375 becomes 9K. 999 becomes 23.98K, which is 99.9% gold, a step under the 100% this site uses for 24K. Type the number into the fineness box and the other two fields follow.
Why does 585 not equal 14K exactly?
14 ÷ 24 is 58.333%, which is 583.3 parts per thousand. The stamp struck on 14K jewelry is 585, and 585 is 58.5%. The jewelry trade uses 585 as the mark for 14 karat. The calculators on this site price a 14K choice as 14/24. If you specifically want 58.5%, type 585 into the fineness field here, then price that percent with Custom purity on the gold calculator.
What is the difference between karat and carat?
Karat, written K, is gold purity out of 24 parts. Carat, written ct, is a gemstone weight of 0.2 grams. A 1 carat diamond says nothing about the gold in the setting. In Britain, gold purity is also written “carat”, so 9ct means 9 karat gold, not a 9 carat stone. The stamp 375 is what confirms it.
Which karat is an unmarked piece?
You cannot tell from the color. Yellow, white and rose are alloy choices, and plating can imitate any of them. Look inside the band, on the clasp or on the bracelet plate for a karat or a fineness number. If there is no stamp, a jeweler can acid-test it or read it with an XRF gun. A magnet is only a rough screen, because many non-gold metals are also non-magnetic.
Does the chart include 8K, 12K and 21K?
Yes. 8K is 33.3% (stamp 333), 12K is 50% (stamp 500), and 21K is 87.5% (stamp 875). Those three do not have their own calculator page. Read the percent here, then enter it as Custom purity on the gold calculator. 21K is a traditional fineness in parts of the Gulf. 8K shows up in some older European pieces.