What does karat mean in gold?

Karat (kt) measures the purity of gold out of 24 parts. 24k is pure gold (99.9%+). 18k means 18/24 = 75% gold. 14k means 14/24 = 58.3% gold. The remaining fraction is alloying metals that improve hardness, workability, and color.

Why are silver, copper, and zinc used as alloying metals?

Copper adds hardness and shifts color toward red/rose. Silver lightens the color and improves ductility. Zinc lowers the melting point, improves flow during casting, and brightens the alloy. The ratio of these three metals determines the final color and working properties of the gold.

What is yellow gold vs. white gold vs. rose gold?

Yellow gold balances copper and silver (roughly equal parts). Rose gold has a high copper ratio and little or no silver. White gold traditionally uses nickel or palladium instead of copper/silver — this calculator focuses on yellow and rose gold alloys using silver/copper/zinc.

How accurate is this calculator?

The math is exact given your inputs. Real-world results depend on how accurately you weigh each metal and on metal purity. Always use a precision scale (0.01 g resolution) and confirm your fine gold is 999.9 or 999 fineness before mixing.

Can I use this for re-alloying scrap gold?

This calculator assumes you start from fine gold (24k). For scrap re-alloying you need to account for the existing karat of the scrap, which requires a blend calculation. This tool covers the fine-gold-plus-alloy approach only.

Gold Alloy Mixer

Name: Gold Alloy Mixer
Availability: InStock
Author: Nham Vu

Calculate how much fine gold and alloying metals to combine to hit a target karat, given the metals you already have on hand.

Gold Target

Target Karat

Custom Karat (1–24)

Batch Weight

Total Weight

Unit

Alloy Metal Ratios

Must total 100%

These percentages apply to the non-gold portion of the alloy only.

Silver (Ag) 40%

Copper (Cu) 55%

Zinc (Zn) 5%

Alloy Recipe

18k

Gold purity

75.00%

750 fineness

Metal	% of batch	Weight (g)
Fine Gold (Au 999)	75.00%	75.00
Silver (Ag)	10.00%	10.00
Copper (Cu)	13.75%	13.75
Zinc (Zn)	1.25%	1.25
Total	100.00%	100.00

Proportion visualization

Fine Gold Silver Copper Zinc

Common Alloy Color Guides

Yellow Gold (18k) Au 75% / Ag 12.5% / Cu 12.5%

Rose Gold (18k) Au 75% / Ag 5% / Cu 20%

Yellow Gold (14k) Au 58.3% / Ag 14% / Cu 28%

Rose Gold (14k) Au 58.3% / Ag 4% / Cu 38%

Click a row to load that preset.

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Summary

Calculate how much fine gold and alloying metals to combine to hit a target karat, given the metals you already have on hand.

How it works

Select or type your target karat (e.g. 14k, 18k, 22k) — this defines the gold purity fraction.
Enter the total batch weight in grams you want to produce.
Adjust the alloy mix ratios: silver, copper, and zinc percentages that will fill the non-gold portion.
The calculator computes fine gold weight from the karat fraction, then splits the remaining weight across your alloy metals.
Review the gram amounts for each metal in the results panel.
Use the copy button to capture the recipe for your workshop notes.

Use cases

Mix a 14k yellow gold alloy batch for casting jewelry.
Create an 18k rose gold alloy by increasing the copper ratio.
Formulate a 22k high-purity alloy for traditional jewelry.
Adjust alloy ratios to fine-tune color (more copper = redder, more silver = greener/paler).
Scale a known alloy recipe up or down to a specific batch weight.
Verify that an existing recipe hits the correct gold purity fraction.

Frequently Asked Questions

Last updated: 2026-06-19 · Reviewed by Nham Vu