Example
Example, not your result- Karat
- 22.00K
- Fineness
- 916.7
- Purity
- 91.67%
- Pure gold weight
- 9.167 g
Reviewed 15 Oct 2026 · by GoldC Team · How we calculate this
Quick answer: what karat means
- 24K = 100% gold, stamped 999
- 22K = 91.67% gold, stamped 916
- 18K = 75% gold, stamped 750
Karat is the number of parts of gold in 24. Divide the karat by 24 to get the purity percentage.
Karat, fineness and purity table
| Karat | Hallmark mark | Exact fineness | Pure gold | Gold in 10 g |
|---|---|---|---|---|
| 24K | 999 | 1,000.0 | 100.00% | 10.000 g |
| 23K | 958 | 958.3 | 95.83% | 9.583 g |
| 22K | 916 | 916.7 | 91.67% | 9.167 g |
| 20K | 833 | 833.3 | 83.33% | 8.333 g |
| 18K | 750 | 750.0 | 75.00% | 7.500 g |
| 14K | 585 | 583.3 | 58.33% | 5.833 g |
| 9K | 375 | 375.0 | 37.50% | 3.750 g |
The hallmark mark is the legal grade stamped on the piece (BIS grades under IS 1417). The exact fineness is the karat divided by 24, so a few marks differ slightly from it: 14K is exactly 583.3 but is stamped 585.
Percent to karat (carat)
Multiply the percentage by 24 and divide by 100 to get the karat. For example, 85% gold is 20.4K.
| Purity % | Karat (carat) |
|---|---|
| 50% | 12.0K |
| 75% | 18.0K |
| 80% | 19.2K |
| 85% | 20.4K |
| 90% | 21.6K |
| 95% | 22.8K |
What carat is a stamped number?
Divide the stamped number by 1,000 and multiply by 24. For example, 585 ÷ 1,000 × 24 = 14.04, so 585 is 14 carat. Here are the stamps people look up most. Any other number works the same way: type it into the converter at the top of this page.
| Stamp | Carat | Gold | Listed in |
|---|---|---|---|
| 375 | 9.0 | 37.5% | UK |
| 417 | 10.0 | 41.7% | |
| 500 | 12.0 | 50.0% | |
| 585 | 14.0 | 58.5% | UK, BIS |
| 595 | 14.3 | 59.5% | |
| 700 | 16.8 | 70.0% | |
| 725 | 17.4 | 72.5% | |
| 750 | 18.0 | 75.0% | UK, BIS |
| 756 | 18.1 | 75.6% | |
| 833 | 20.0 | 83.3% | BIS |
| 850 | 20.4 | 85.0% | |
| 875 | 21.0 | 87.5% | |
| 916 | 22.0 | 91.6% | UK, BIS |
| 958 | 23.0 | 95.8% | BIS |
| 999 | 24.0 | 99.9% | UK, BIS |
In the last column UK means the UK hallmarking list and BIS means India's hallmark grades; an empty cell means the sources listed below don't name that number as a standard grade. The carat is rounded to one decimal.
How the conversion works
- Purity % = karat ÷ 24 × 100
- Fineness = karat ÷ 24 × 1000 (parts of gold in every thousand)
- Karat = fineness ÷ 1000 × 24, or purity % ÷ 100 × 24
- Pure gold weight = total weight × purity %
Worked examples
22K gold: 22 ÷ 24 = 91.67% pure, fineness about 916.7. A 10 g piece holds 9.167 g of pure gold.
18K gold: 18 ÷ 24 = 75% pure, fineness 750. A 10 g piece holds 7.5 g of pure gold.
Stamped 750: 750 ÷ 1000 × 24 = 18K.
Reading a gold hallmark
India (BIS): a hallmarked piece carries the BIS mark, the purity and fineness mark such as 22K916, and a 6-character HUID code. The grades in use are 24K999, 23K958, 22K916, 20K833, 18K750, 14K585 and 9K375.
UK and the Hallmarking Convention: the fineness is a number without the karat, and the standard grades are 375 (9 carat), 585 (14 carat), 750 (18 carat), 916 (22 carat) and 999. Each assay office adds its own mark, for example a leopard's head for London and an anchor for Birmingham.
Hallmark numbers are rounded legal grades, so they can differ from the exact fraction by a fraction of a point, as with 14K (583.3 exact, 585 stamped) and 22K (916.7 exact, 916 stamped).
Quick answers
Is 22K gold the same as 916?
They name the same grade. 22K is 22 parts of gold in 24, exactly 91.67%, while the legal hallmark grade is 916 (91.6%). The mark 916 is what is stamped on 22K gold in India and the UK.
Is 24K gold really 100% pure?
24K is the purest grade. In practice it is stamped 999 (99.9%), so gold marked 24K999 is treated as pure gold.
Why is jewellery usually 22K or 18K?
Pure gold is soft. Alloying it with other metals makes jewellery stronger, and the karat tells you how much gold is left.
What carat is 375 gold?
9 carat. 9 parts of gold in 24 is 37.5% gold, and 375 is the number stamped on it. What 375 means on gold explains the hallmark.
What carat is 750 gold?
18 carat. 750 parts of gold in 1,000 is 75% gold, which is 18 parts in 24.
Sources
- Trading Standards: Hallmarking Act: UK gold fineness standards 375, 585, 750, 916
- BIS hallmarking FAQ: permitted gold grades, the BIS mark and HUID (read 8 October 2026)
- GOV.UK hallmarking guidance summary: the compulsory UK hallmark marks (read 8 October 2026)
- Assay Office London: What is a hallmark: the fineness marks 375, 585, 750, 916 and 999 (read 8 October 2026)
Reviewed 15 October 2026. Reference tool only; not advice.
Disclaimer: Purity calculations are approximate and may vary by alloying and testing methods.