Gold Purity Converter (Karat to Percent)
22K = 91.67 % = 916, 18K = 750 — plus pure gold by weight and alloying sums.
Type in any box: karat (22), purity in % (91.6) or fineness in parts per thousand (916).
- Karat
- 22K
- Gold
- 91.667 %
- Parts per 1000
- 916.7
22K is 91.667 % gold in theory; BIS hallmarks it as 916 (91.6 %).
Pure gold in an item
10 g of 22K holds 9.167 g of pure gold and 0.833 g of other metals.
At the hallmark fineness 916: 9.16 g of gold.
Change the karat: what to add
Starting from the item above: 10 g of 22K (91.667 %).
Karat (18), fineness (750) or % (75).
Gold karat chart
Karat ÷ 24 is the share of pure gold. Hallmarks stamp the fineness; BIS grades are those of IS 1417. Your purity is highlighted.
| Karat | Gold % (exact) | Parts per 1000 (exact) | Hallmark | BIS grade |
|---|---|---|---|---|
| 24K | 100 | 1,000 | 999 / 995 | 24K 995 |
| 23K | 95.833 | 958.3 | 958 | 23K 958 |
| 22K | 91.667 | 916.7 | 916 | 22K 916 |
| 21K | 87.5 | 875 | 875 | — |
| 20K | 83.333 | 833.3 | 833 | 20K 833 |
| 18K | 75 | 750 | 750 | 18K 750 |
| 16K | 66.667 | 666.7 | — | — |
| 15K | 62.5 | 625 | — | — |
| 14K | 58.333 | 583.3 | 585 | 14K 585 |
| 12K | 50 | 500 | — | — |
| 10K | 41.667 | 416.7 | 417 | — |
| 9K | 37.5 | 375 | 375 | — |
| 8K | 33.333 | 333.3 | 333 | — |
| Fineness | Silver % | Name | BIS grade |
|---|---|---|---|
| 999 | 99.9 | Fine silver | — |
| 990 | 99 | — | Yes |
| 970 | 97 | — | Yes |
| 925 | 92.5 | Sterling silver | Yes |
| 900 | 90 | — | Yes |
| 835 | 83.5 | — | Yes |
| 800 | 80 | — | Yes |
About the Gold Purity Converter (Karat to Percent)
Convert the purity of gold between karat, percent and fineness (parts per thousand, the number stamped in a hallmark) — type in any of the three boxes and the other two follow. 22 karat is 22/24 = 91.67 % pure gold in theory and is hallmarked 916; 18 karat is exactly 75 %, hallmarked 750. Switch to silver for fineness grades such as 925 sterling.
The converter also works out how much pure gold or silver an item holds from its weight in grams, tola or troy ounces, and how much fine gold or alloy to add to reach another karat. It names the nearest standard grade and the BIS hallmark grades used in India.
How to use it
- Choose Gold or Silver, then type the purity in any box: the karat (22), the purity in % (91.6) or the fineness (916). A hallmark such as
22K916typed in the karat box is read too. - Read the purity in all three forms and the line about hallmarks: whether it is a standard grade, and for whole karats the fineness it is hallmarked at.
- In Pure gold in an item, enter the weight and its unit (grams, tola, troy ounces) to see the pure metal and the other metals in it.
- In Change the karat, type the purity you want (for example 18K, 750 or 75 %) and choose what to add; the result gives the weight to add and the final weight.
- Use the karat chart (or the silver chart) for every common karat and grade; copy it, download it or print it.
Examples
22K
91.667 % gold = 916.7 parts per thousand; hallmarked 916 (91.6 %)
22 ÷ 24 = 0.91666…
Fineness 750
18K = 75 % gold
Fineness 585
14.04 karats; 14K in theory is 583.3
The hallmark grade is a little above the plain fraction 14/24.
10 g of 22K
9.167 g of pure gold (9.16 g at the hallmark fineness 916)
1 tola of 22K
0.9167 tola = 10.692 g of pure gold
10 g of 18K, add fine gold 999
Add 20.243 g of fine gold 999 → 30.243 g of 22K
10 g of fine gold 999, add an alloy with no gold
Add 0.898 g of alloy → 10.898 g of 22K
Common uses
- Reading the purity stamped on jewellery (916, 750, 585) as a karat value or a percentage.
- Working out the pure gold in an item from its weight, before selling, exchanging or valuing it.
- Comparing gold sold in different karats — 24K, 22K, 21K, 18K, 14K and 9K — by the pure gold each holds.
- Planning a mix at the bench: how much fine gold raises an alloy to 22K, or how much alloy brings fine gold down to 18K.
- Checking silver: 925 sterling, 999 fine silver and the BIS silver grades.
Karat, percent and fineness
A karat counts parts of pure gold in 24: 24K is pure gold and 18K is 18 parts gold to 6 parts other metals. The percentage is karat ÷ 24 × 100, and the fineness is the same share in parts per thousand, karat ÷ 24 × 1000:
- 24K = 100 % = 1000 (bars and coins are sold as 999 or 995)
- 22K = 91.667 % = 916.7, hallmarked 916
- 18K = 75 % = 750
- 14K = 58.333 % = 583.3, hallmarked 585
- 9K = 37.5 % = 375
The other way round, karat = fineness × 24 ÷ 1000: a stamp of 916 is 21.98 karats and 585 is 14.04 karats. A karat (K or kt) measures purity; a carat (ct) is a weight for gemstones, 200 mg — the two are easily confused.
Hallmarks in India (BIS)
The Bureau of Indian Standards hallmarks gold in the grades of IS 1417: 14K 585, 18K 750, 20K 833, 22K 916, 23K 958 and 24K 995, and silver in the grades of IS 2112: 800, 835, 900, 925, 970 and 990 (BIS hallmarking FAQs). A BIS hallmark on gold has three marks: the BIS logo, the purity in karat and fineness (for example 22K916) and a six-digit alphanumeric HUID that you can check in the BIS Care app.
Notice that 22K916 is a shade below the plain fraction 22/24 (916.7), while 14K585 is a shade above 14/24 (583.3). The converter shows both, and in Pure gold in an item it works out the gold at the karat value and at the hallmark fineness.
The alloying sum
Mixing a mass M of an alloy of fineness F with x of a second metal of fineness A gives the fineness T when
x = M × (F − T) ÷ (T − A)
To raise the karat, add a richer metal (fine gold, A = 999 or 1000); to lower it, add a leaner one — an alloy with no gold (A = 0), usually of silver and copper. For example 10 g of 18K needs 10 × (750 − 916.7) ÷ (916.7 − 1000) = 20 g of pure gold to become 22K. The sum assumes no metal is lost in melting; in practice a little is, so a refiner or assayer should confirm the result.
Limitations
- This converts and calculates; it does not test metal. Only an assay, such as that of a BIS Assaying and Hallmarking Centre, shows the real purity of an item.
- Weights are of the metal only: subtract stones, enamel and wax before working out the pure gold.
- Prices are not part of this tool; use the Gold & Silver Price Calculator for the value of an item.
- Platinum and palladium grades are not covered.
Privacy
Everything happens in your browser. What you enter or open here is not uploaded or stored by MySmartCoPilot.
Frequently asked questions
What percentage of gold is 22 karat?
91.67 % in theory (22 ÷ 24). BIS hallmarks it as 916, which is 91.6 %.
What does 916 on gold mean?
The gold is 916 parts per thousand pure, 91.6 %: 22 karat. In India the hallmark reads 22K916, with the BIS logo and a six-digit HUID.
Is 18K gold 75 % gold?
Yes: 18 ÷ 24 = 75 %, stamped 750. The other 25 % is a mix of metals such as silver and copper.
How much pure gold is in 10 grams of 22K?
9.167 g in theory (10 × 22 ÷ 24), or 9.16 g at the hallmark fineness 916.
What karat is 585 gold?
14 karat: 585 parts per thousand is 58.5 % gold, 14.04 karats. 14/24 is 583.3; the hallmark grade is set slightly higher.
What is 925 silver?
Sterling silver: 925 parts per thousand, 92.5 % pure silver. It is one of the BIS silver grades (800, 835, 900, 925, 970 and 990).
What is the difference between karat and carat?
A karat (K, kt) measures the purity of gold out of 24. A carat (ct) is the weight of a gemstone: 1 ct = 200 mg.