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Find the pure gold and impurity content of any gold item based on weight and karat.
Gold & Silver
Generated on May 23, 2026
Find the pure gold and impurity content of any gold item based on weight and karat.
A gold purity calculator splits any weight of gold into its two components: the pure 24K gold content and the alloy (impurity) content. This is essential for insurance declarations, inheritance valuations, Zakat computation (which is based on pure gold weight), melting and recasting calculations, and anyone comparing 22K vs 18K purchases. The calculator accepts any weight unit (grams, tola, masha, ratti, or ounces) and any karat from 10K through 24K, showing both the pure gold equivalent and the impurity (alloy) breakdown in all common units, along with a visual purity-vs-impurity split bar.
Formula
Pure Gold = Total Weight × (Karat ÷ 24). Impurity = Total − Pure.You inherited a piece marked 'gold' and want to know whether it's 22K, 18K, or 9K before walking into Sarafa Bazar. The stamp inside the clasp (916, 750, 585) is a karat number disguised as parts-per-thousand: 916 means 22K, 750 means 18K, 585 means 14K. No stamp at all is suspicious; pre-1960s Indian and Pakistani gold often went unhallmarked, but most of it is still high-purity 22K because that's what jewellers worked in. This calculator splits any gold weight into its two components — the pure 24K gold content and the alloy (impurity) — for any karat from 10K through 24K, in grams, tola, masha, ratti, or troy ounces. Essential for insurance declarations (insurers want pure-gold weight, not gross), inheritance valuations where someone needs to split a 12-tola 22K necklace fairly, Zakat computation (which is calculated on PURE gold weight, not gross jewellery weight — getting this wrong means underpaying or overpaying Zakat), and anyone trying to decide whether 22K or 18K makes more financial sense for a bridal set. Honest take: never sell the same day you walk in for a quote — get three quotes from different shops, all on the same morning before the international rate fluctuates. The 5 percent spread between the highest and lowest offer for the same piece is real, and aunties who've sold five times know which corner shop pays best.
A gold purity calculator splits any weight of gold into its two components: the pure 24K gold content and the alloy (impurity) content. This is essential for insurance declarations, inheritance valuations, Zakat computation (which is based on pure gold weight), melting and recasting calculations, and anyone comparing 22K vs 18K purchases. The calculator accepts any weight unit (grams, tola, masha, ratti, or ounces) and any karat from 10K through 24K, showing both the pure gold equivalent and the impurity (alloy) breakdown in all common units, along with a visual purity-vs-impurity split bar.
Karat expresses gold purity as parts out of 24. So 22-karat gold is 22 parts pure gold and 2 parts alloy (usually copper, silver, or zinc for hardness and color), making 22/24 = 91.67% purity. 18K is 75% pure. Multiplying the total weight by this fraction gives the pure-gold content; the remainder is the impurity or alloy weight. Notice that jewellers often use the terms 'purity' and 'alloy' interchangeably — they describe the same split from opposite sides of the ratio.
The definitive karat-to-purity chart with equivalent fineness and hallmark stamps.
| Karat | Purity % | Fineness (parts per 1000) | Hallmark Stamp | Common Use |
|---|---|---|---|---|
| 24K | 99.99% | 999 | 999 / 24K | Pure bullion bars, investment coins |
| 22K | 91.67% | 916 | 916 / 22K | Most Pakistani / Indian gold jewellery |
| 21K | 87.50% | 875 | 875 / 21K | Popular in Gulf markets (UAE, KSA) |
| 20K | 83.33% | 833 | 833 / 20K | Traditional South Asian pieces |
| 18K | 75.00% | 750 | 750 / 18K | Fine western jewellery, diamond settings |
| 14K | 58.33% | 583 | 583 / 14K | US mass-market jewellery |
| 10K | 41.67% | 417 | 417 / 10K | Minimum legal gold in US, cheap items |
| 9K | 37.50% | 375 | 375 / 9K | Minimum legal gold in UK |
24K gold is so soft (hardness ~2.5 on Mohs scale) that you can dent it with a fingernail — which is why jewellery rarely uses it.
22K gold (91.67% pure) is the sweet spot for Pakistani/Indian wedding jewellery — enough purity for resale value, enough alloy for durability.
18K (75% gold) is the global premium standard for fine western jewellery — Tiffany, Cartier, and Bulgari mostly use 18K.
A hallmark stamp of '916' on Pakistani gold means 22K purity — one of the most important checks when buying.
10 tola of 22K gold contains 10 × 22/24 = 9.17 tola of pure gold and 0.83 tola of alloy.
50 g of 18K gold contains 50 × 18/24 = 37.5 g of pure gold and 12.5 g of alloy metals.
A 100 g 14K US necklace contains only 58.33 g of actual gold — the rest is copper, silver, or zinc alloy.
For Zakat purposes: 50 tola of 22K gold has 45.83 tola of pure gold, which is compared against the Nisab threshold for obligation.
A 200 g 21K Middle-Eastern bangle set contains 175 g pure gold (21/24 × 200) and 25 g alloy.
Melting down a 15 g 14K ring yields only 8.75 g of recoverable pure gold — useful to know when considering melting for remake.
Jump to a ready-made conversion — useful for quick reference and sharing:
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