Gold Purity Calculator
Gold percent, parts, and alloy from karat.
What it does
Karat counts gold in twenty-fourths: 24K runs pure while 14K splits 14 parts gold against 10 alloy. Color and hardness ride the alloy; value rides the share.
The tool above takes karat. It returns gold percent, parts, and alloy share.
The default 14K reads 58.3% gold with 41.7% alloy. The 24K case reads 100% with none, and 10K reads 41.7% with 58.3% alloy.
Fineness standards define gold share in parts per thousand, matching karat over 24 exactly. Trade guidance repeats the division for descriptions and hallmarks.
Stamps invite trust but assays decide: fakes stamp high while acid and XRF read true. Separate this purity ruler from carat weight, which weighs stones, not gold.
How to use
- Type the karat.
- Read gold percent first.
- Read parts beside it.
- Read alloy last.
- Assay stamped bargains.
- Separate carat weight math.
Formula
- K
- Gold karat, 1 to 24.
- gold%
- Gold share by weight.
- alloy
- Non gold share.
ISO 9202 sets gold fineness in parts per thousand matching karat over 24, and jeweler guidance repeats the same division for trade descriptions. Carat weight for stones is the separate 0.2 gram ruler. Millesimal marks round trade convention, so percent math rules disputes.
Worked example
Example: 14K ring
Default: 14 karat.
- Ring: 14 karat gold.
- Pure: 14 / 24 x 100 = 58.3% gold.
- Parts: 14 of 24 parts gold.
- Alloy: 100 minus 58.3 = 41.7% alloy.
- Check: 585 hallmark rounds trade mills.
- Tool shows 58.3% gold, 14 of 24 parts, 41.7% alloy.
Reference table
| Karat | Gold | Alloy |
|---|---|---|
| 24K | 100% | 0% |
| 18K | 75% | 25% |
| 14K | 58.3% | 41.7% |
| 10K | 41.7% | 58.3% |
Limits
- Share math only.
- Alloy mix unread.
- Plating fools surface tests.
- Marks vary by country.
Common mistakes
- Reading karat as carat.
- Trusting stamps blindly.
- Pricing by color alone.
- Ignoring solder dilution.
- Testing plated surfaces.
Try it yourself
Quick checks. Answers sit tucked under each question.
24 karat?
100% gold with 0% alloy.
10 karat?
41.7% gold with 58.3% alloy.
30 karat?
Over 24 exceeds pure: enter 1 to 24 karat.
Questions
Karat to percent?
Karat over 24 times 100. 14K is 58.3%, 18K is 75%, 24K is 100%.
Alloy metals?
Copper, silver, nickel, zinc, and palladium tune color and hardness.
Color changes purity?
Yellow, white, and rose all assay the same gold share at equal karat.
Karat or carat?
No, karat purifies with a K while carat weighs diamonds with a C. This page purifies.
Test stamps?
Yes, by assay: stamps lie on fakes, acid and XRF tell truth.
Tarnish?
Skin, sweat, and sulfur dull alloys while pure gold shrugs. Rinse and dry after wear.