Convert Karats (K) to Fineness (per mille) (‰ fine)
Karats and fineness are two spellings of the same fact: how much of the metal is actually gold. 18K means 18/24 gold — exactly 750 fineness, the number stamped inside the ring.
Formula
1 K = 41.666667 ‰ fine
To convert K to ‰ fine, multiply the value by 41.666667.
Conversion Table
| Karats (K) | Fineness (per mille) (‰ fine) |
|---|---|
| 1 K | 41.6667 ‰ fine |
| 2 K | 83.3333 ‰ fine |
| 4 K | 166.6667 ‰ fine |
| 6 K | 250 ‰ fine |
| 8 K | 333.3333 ‰ fine |
| 9 K | 375 ‰ fine |
| 10 K | 416.6667 ‰ fine |
| 12 K | 500 ‰ fine |
| 14 K | 583.3333 ‰ fine |
| 16 K | 666.6667 ‰ fine |
| 18 K | 750 ‰ fine |
| 20 K | 833.3333 ‰ fine |
| 21 K | 875 ‰ fine |
| 21.6 K | 900 ‰ fine |
| 22 K | 916.6667 ‰ fine |
| 23 K | 958.3333 ‰ fine |
| 24 K | 1000 ‰ fine |
Common K to ‰ fine Examples
- 8 K = 333.3333 ‰ fine
- 9 K = 375 ‰ fine
- 10 K = 416.6667 ‰ fine
- 14 K = 583.3333 ‰ fine
- 18 K = 750 ‰ fine
- 21.6 K = 900 ‰ fine
- 22 K = 916.6667 ‰ fine
- 24 K = 1000 ‰ fine
About K to ‰ fine
The conversion is fineness = karat × 1000 ÷ 24. The common jewellery grades line up like this: 24K = 999 (bullion), 22K = 916 (Indian and Gulf jewellery), 18K = 750 (fine European jewellery), 14K = 585 (the everyday standard in the US and much of Europe), 9K = 375 (budget UK gold).
Hallmarks stamp the fineness, shops talk in karats — so reading "585" on a clasp and knowing it is 14K is exactly this conversion. Do not confuse karat (purity) with carat (gem weight, 0.2 g).
About the units
Karats (K) — The karat measures gold purity in 24ths: 24K is pure gold, 18K is 75% gold, 14K is 58.3%. Not to be confused with the carat, which is a gemstone weight (0.2 g).
Fineness (per mille) (‰ fine) — Fineness states precious-metal purity in parts per thousand — the "750" stamped inside an 18K ring or "925" on sterling silver. Bullion is marked 999 or 999.9.
Frequently Asked Questions
What fineness is 18K gold?
750 — meaning 750 parts per thousand, or 75% pure gold. That is the "750" hallmark inside 18K jewellery.
Is 916 gold the same as 22K?
Yes. 22 ÷ 24 × 1000 ≈ 916.7, so the "916" stamp on Indian and Middle Eastern jewellery is 22-karat gold.
Why is the conversion factor between K and ‰ fine 41.666667?
It comes from the official definitions of both Gold Purity units, which are anchored to internationally agreed reference standards.
What is a quick way to estimate K to ‰ fine?
Round 41.666667 to one or two significant digits and multiply mentally. Use the exact factor when accuracy matters.
How is ‰ fine used in everyday life?
Fineness (per mille) is commonly seen in regions and contexts where it is the preferred Gold Purity unit, from signage to technical specifications.
How is K used in everyday life?
Karats appears in measurements, product labels, and reports wherever the local convention favors that unit for Gold Purity.
Which industries rely on K to ‰ fine conversions?
Logistics, manufacturing, scientific research, and international commerce all routinely move between K and ‰ fine.
What are common uses for converting K to ‰ fine?
Typical scenarios include travel, trade, engineering, science, and any situation where data is reported in K but needed in ‰ fine.