Gold Karat Converter
Preserve pure-gold content; see equivalent mass at any target karat.
Convert a gold piece’s mass between karats while keeping the pure-gold content constant. Enter grams, pick a starting karat, and choose a target — the converter returns the equivalent mass and shows how much alloy is added or removed.
- Starting mass
- 10 g 24K
- Starting purity
- 100.00%
- Pure gold
- 10.000 g
- Target purity
- 91.67%
- Target mass
- 10.909 g
- Mass Δ
- +0.909 g
- 9K
- 26.667 g
- 10K
- 24.000 g
- 12K
- 20.000 g
- 14K
- 17.143 g
- 18K
- 13.333 g
- 20K
- 12.000 g
- 21K
- 11.429 g
- 22K
- 10.909 g
- 24K
- 10.000 g
The math
pure_gold = mass × (from_karat ÷ 24)
target_mass = pure_gold × (24 ÷ to_karat)
Karat expresses the proportion of pure gold in 24 parts. 24K is 99.9%+ pure. 22K is 22/24 = 91.67% pure. 18K is 75%. 14K is 58.33%. 10K is 41.67%. The remainder is alloy metals (mostly copper, silver, zinc, nickel) added for hardness and color.
How to use
- Enter the mass in grams.
- Pick the starting karat.
- Pick the target karat.
- Read the target mass and the alloy delta.
Examples
What users are actually trying to do
- ▸ Estimating equivalent jewelry weights at different purities
- ▸ Checking a seller’s claim that a piece is a certain karat
- ▸ Converting between Indian (22K), European (18K), and US (14K) jewelry standards
- ▸ Understanding pure-gold content when buying or selling
Common mistakes
- ! Assuming equal mass at a different karat (purity is the invariant, not mass)
- ! Forgetting that lower karat means more mass for the same gold
- ! Thinking you can down-karat a piece at home (you can’t — it requires refining)
Before you trust the result
Check the inputs that matter most: dates, rates, units, costs, and any optional fields you skipped. A calculator can only work with the numbers entered here, so use the result as a decision check rather than a final answer when money, health, tax, legal, or safety consequences are involved.
If the result feels surprising, change one input at a time and watch which number moves. That usually shows the real lever behind the decision.
Limitations
- · Pure-purity math only — assumes standardized karat definitions
- · No alloy composition modeling (rose vs yellow vs white gold share karat but differ in alloy metals)
- · No density calculation
Next up
Frequently asked questions
› How do you convert 24K gold to 22K gold? How-to
Keep the pure-gold mass constant and add alloy. Pure gold mass equals starting mass times (starting karat / 24). Target mass equals pure gold times (24 / target karat). 10 g of 24K becomes 10.909 g of 22K.
› How much gold is in 14K? Definition
14K gold is 14/24 = 58.33% pure gold by weight. 10 g of 14K contains 5.833 g of pure gold.
› How do you turn 24K into 18K? How-to
Mathematically: 10 g of 24K = 13.333 g of 18K. Physically, this requires refining — alloy metals (copper, silver, zinc) are added. Most people sell and re-buy rather than refine at home.
› Is higher karat always better? Comparison
Higher karat means more pure gold but softer metal. 18K and 22K are the common premium jewelry karats because 24K is too soft to hold gemstones or survive daily wear.
› What percent of 22K gold is pure gold? Definition
22K gold is 22/24 = 91.67% pure gold. The remainder (8.33%) is alloy metals.
Related tools
Gold Value Calculator
Estimate the melt value of gold jewelry or bullion by weight, karat, and the current spot price per gram.
Percent Of Calculator
Calculate exactly what X% of Y equals, with quick-math anchors for 1%, 10%, 25%, and 50%.
Percentage Calculator
Calculate percentages: what is X% of Y, X is what % of Y, and % change.