Alloy Calculator.
Carit's alloy calculator tells you exactly how much of each base metal to combine to hit a target karat and total weight. Works for every common gold karat (9k, 10k, 14k, 18k, 22k) in yellow, white and rose - plus sterling silver and platinum mixes. Inside the Carit app on iOS and Android.
Get the alloy calculator in the Carit app.
Every gold, silver and platinum mixing recipe a bench jeweller reaches for, with exact quantities and master-alloy awareness. Free tier + 3-session trial. Pro at $8.99/month or $69.99/year.
How alloy mixing actually works
Every gold alloy is a blend. Pure gold (24k, 999 fine) is too soft for most jewellery use, so it's mixed with base metals - copper, silver, zinc, nickel (in older white golds), palladium (in modern whites) - to raise hardness, shift colour, and hit the target karat. The karat number is the fraction of pure gold by weight: 18k means 18/24 = 75% pure gold, 14k means 14/24 = 58.3%, 9k means 9/24 = 37.5%.
When you're grain-casting your own alloys rather than buying pre-mixed grain, the math is straightforward: for every 100 g of alloy you want to produce at karat K, you need K × 100 / 24 grams of pure 24k gold and (24 − K) × 100 / 24 grams of master alloy.
Master alloy needed = (24 − Target karat) / 24 × Total alloy weight
What makes it tricky in practice is that "master alloy" isn't one thing. It's a proprietary blend that varies between refiners - yellow master has a different copper/silver ratio than white master, and both differ from rose master. So Carit's calculator doesn't just output "75 g pure + 25 g master". It outputs the exact base-metal breakdown behind the master for whichever colour you're targeting.
Standard gold alloy recipes
These are the industry-reference base-metal breakdowns used for most commercial goldsmithing. Carit's calculator uses these as defaults but lets you override the master-alloy recipe for workshops that grain their own custom colours.
| Alloy | Fine gold | Silver | Copper | Other |
|---|---|---|---|---|
| 18k yellow gold | 75.0% | 12.5% | 12.5% | - |
| 18k white gold (Pd) | 75.0% | - | - | 25% Palladium |
| 18k white gold (Ni) | 75.0% | 2% | 5% | 18% Nickel (being phased out) |
| 18k rose gold | 75.0% | 4% | 21% | - |
| 14k yellow gold | 58.3% | 25% | 16.7% | - |
| 14k white gold (Pd) | 58.3% | - | - | 41.7% Palladium / mix |
| 14k rose gold | 58.3% | 10% | 31.7% | - |
| 10k yellow gold | 41.7% | 11% | 47.3% | - |
| 9k yellow gold | 37.5% | 11% | 51.5% | - |
| 22k yellow gold | 91.7% | 4% | 4.3% | - |
Worked examples from the Carit calculator
Make 100 g of 18k yellow gold from scratch
Using the standard recipe: 75 g of 24k fine gold + 12.5 g silver + 12.5 g copper. Melt the base metals together first to form a homogeneous master, then add the fine gold. Alternatively, Carit can output: 75 g fine gold + 25 g pre-mixed yellow master alloy.
Make 50 g of 14k rose gold
Standard 14k rose recipe: 29.15 g fine gold + 5 g silver + 15.85 g copper. The copper-heavy mix is what gives 14k rose its warm, saturated pink tone.
Up-karat 50 g of 14k yellow to 18k yellow
Useful when you have 14k scrap and need 18k grain. Carit handles the reverse calculation: adding X grams of fine gold to Y grams of 14k alloy to hit 18k purity. For 50 g of 14k yellow (containing 29.15 g fine), adding 33.4 g of fine gold gives 83.4 g of 18k yellow (with the right base-metal proportions preserved).
Down-karat with scrap
Also works in reverse - diluting 18k down to 14k by adding master alloy. Carit handles the stoichiometry so your calculated mix hits the exact target karat.
Silver, platinum and palladium alloys
Carit covers the full range of common silver and platinum alloys:
- Sterling silver (.925): 92.5% fine silver + 7.5% copper (standard) or 7.5% germanium / other anti-tarnish modifiers
- Britannia silver (.958): 95.8% fine silver + 4.2% copper (UK hallmark standard, softer, tarnish-resistant)
- Argentium silver: 93.5% fine silver + 6.5% with germanium (proprietary anti-tarnish)
- Platinum 950: 95% platinum + 5% cobalt or ruthenium (industry standard for jewellery)
- Platinum 900: 90% platinum + 10% iridium (slightly softer, more workable)
- Palladium 950: 95% palladium + 5% ruthenium or copper
Why calculate the alloy?
Four reasons a bench jeweller runs this calculation rather than buying pre-mixed grain:
- Cost - buying fine gold + master alloy separately is cheaper than buying pre-mixed grain at the same karat. Over a year of castings, the difference is real.
- Custom colours - no refiner sells exactly the 18k rose you want. Graining your own lets you tune the copper ratio to hit the exact pink.
- Scrap recycling - shop scrap, failed castings, old commissions - these get refined down to fine gold and re-alloyed. The calculator tells you how much master to add to hit the target karat.
- Hallmark certainty - if you're assaying in-house, knowing the exact proportions gives you a defensible assay number.
Carit's alloy calculator handles every variant.
Custom master alloy recipes, scrap reclamation, up-karating, down-karating, silver and platinum alloys - all in one tool. Free to download, full calculator unlocks with Carit Pro.
While you're here
- Metal weight calculator - once you've alloyed, calculate casting weight
- Goldsmith calculator - the full goldsmithing toolkit documented
- All Carit calculators →