Gold Purity Calculator - Karat, Percentage, Touch & Tunch Online

Free Online Gold Purity Calculator (Karat ↔ Percentage ↔ Touch)

Convert between karat (24K, 22K, 18K, 14K, 10K), purity percentage (99.9%, 91.6%, 75%, 58.5%, 41.7%), touch / tunch and a 3-digit hallmark (999, 916, 750, 585, 375). Enter a value to see its equivalents.

Use the calculator to understand a stamp on jewellery, compare a jeweller's purity quote or work out the gold content used in a melt-value estimate. In South Asian jewellery trade, a quote of 91.6 touch refers to 22K gold. The calculator shows these terms together so you can compare them without switching scales yourself.

How the Purity Conversion Works

Each scale describes the proportion of gold in an alloy. The rest may include metals such as copper, silver, zinc or palladium. The calculator uses the ratio of pure-gold mass to total mass to convert between karat, percentage, touch and fineness marks.

Change a purity value and the other fields update. If you also enter the total weight in grams, the calculator shows the estimated pure-gold weight in grams, troy ounces and standard ounces. This is a conversion based on the purity you provide, not a test of the metal itself.

Features

• Conversion in either direction: change karat, percentage, touch/tunch or hallmark fineness to see the other values.

• Common karat presets: select 24K (999), 22K (916), 21K (875), 20K (833), 18K (750), 14K (583), 12K (500), 10K (417), 9K (375) or 8K (333).

• Pure-gold weight: enter the total weight in grams to see the gold content in grams, troy ounces and avoirdupois ounces.

• Touch and tunch: compare terminology used by jewellers in India and South Asia, including 91.6 touch = 22K and 75 touch = 18K.

• Fineness marks: compare purity values with marks such as 999, 958, 916, 875, 750, 585 and 375. Reading a mark's numeric meaning does not verify its certification.

• Browser-based calculation: conversions update as you type, without a Tooloogle signup or an upload of your calculation values.

Quick Reference: Karat ↔ Purity Percentage ↔ Hallmark ↔ Touch

Use this table to compare common purity labels. The values follow rounded trade conventions.

How to Use the Gold Purity Calculator

1. Enter a karat value. The percentage, touch and fineness mark update alongside it.

2. Or enter a percentage. Read the corresponding karat, touch and fineness values, allowing for the calculator's rounding.

3. Or enter a touch value. Use this field if your jeweller quoted purity in touch or tunch; the karat and percentage update with it.

4. Or select a preset. Choose a chip such as 24K, 22K, 18K, 14K or 10K to load that purity.

5. Add the total weight in grams if needed. The calculator shows the estimated pure-gold weight in grams and troy ounces.

6. Read the value you need. Use karat for comparing jewellery, percentage for gold content, touch for a retailer's quote or the fineness value to understand a numeric stamp.

Karat and Purity Formulas

The karat scale measures gold content out of 24 parts. To convert a karat value to a percentage, divide it by 24 and multiply by 100:

Purity % = (Karat / 24) × 100

To convert a percentage back to karat:

Karat = (Purity % / 100) × 24

For example, 18K is (18 / 24) × 100 = 75% pure. For 22K, (22 / 24) × 100 = 91.66...%; the common 916 fineness label represents 91.6%. In the other direction, 60% purity gives (60 / 100) × 24 = 14.4 karat. Keep the calculated value separate from any rounded commercial label.

The 3-Digit Hallmark Decoded

A fineness number expresses gold content in parts per thousand rather than a percentage. For example, 99.9% corresponds to 999, 91.6% to 916, 75% to 750, 58.5% to 585 and 37.5% to 375. This explains the numeric part of a stamp; it does not establish whether a piece or its hallmark is genuine.

What "Touch" and "Tunch" Mean

Jewellers in the Indian subcontinent may quote purity as "touch", "tunch" or "tanch". In this usage, the value matches the percentage without the "%" sign. A quote of 91.6 touch refers to 22K (91.6% pure), 75 touch to 18K (75% pure), and 99.9 touch to 24K (99.9% pure).

These terms describe purity, not proof of a particular certification. The calculator displays touch beside karat so you can compare the terms used in a retailer's quote.

Common Conversion Examples

How to Calculate Karat From a Percentage

If a listing describes an item as "88% gold", calculate 88 / 100 × 24 = 21.12. That is roughly 21K. The examples below show other percentage-to-karat conversions and rounded trade labels:

• 65% gold → 15.6 karat (sold as 15K or 16K)

• 71% gold → 17.04 karat (sold as 17K)

• 73% gold → 17.5 karat (sold as 17K or 18K)

• 74% gold → 17.76 karat (close to 18K)

• 80% gold → 19.2 karat (sold as 19K)

• 81% gold → 19.44 karat (sold as 19K)

• 82% gold → 19.68 karat (close to 20K)

• 85% gold → 20.4 karat (sold as 20K)

• 87% gold → 20.88 karat (close to 21K)

• 88% gold → 21.12 karat (sold as 21K)

• 91.6% gold → 22 karat (BIS-916 hallmark)

How to Calculate Percentage From a Karat

For a 19K ring, calculate 19 / 24 × 100 = 79.17%. Other common karat values and their percentages are listed below:

• 16K → 66.7%

• 18K → 75% (hallmark 750)

• 19K → 79.2%

• 19.5K → 81.25%

• 20K → 83.3%

• 21K → 87.5% (hallmark 875)

• 21.5K → 89.6%

• 22K → 91.6% (hallmark 916)

• 23K → 95.8% (hallmark 958)

• 23.5K → 97.9%

• 24K → 99.9% (hallmark 999)

Comparing Gold Content Across Karats

• 22K to 24K conversion: 1 gram of 22K (91.6% pure) contains 0.916 grams of pure gold, equivalent to 0.916 grams of 24K using this convention.

• 18K to 24K conversion: 1 gram of 18K (75% pure) contains 0.75 grams of pure gold, equivalent to 0.75 grams of 24K using this convention.

• 14K to 24K conversion: 1 gram of 14K (58.5% pure) contains 0.585 grams of pure gold.

• 10K to 24K conversion: 1 gram of 10K (41.7% pure) contains 0.417 grams of pure gold.

• 916 to 22K: the 916 fineness mark is commonly associated with 22K (91.6%).

• 750 to 18K: the 750 fineness mark corresponds to 18K (75%).

• Pure gold to 916 conversion: divide by 0.916. So 10 grams of pure gold equals 10 / 0.916 = 10.92 grams of 916 (22K) alloy.

Pure-Gold Weight in Common Pieces

• 4 grams of 18K gold: 4 × 0.75 = 3 grams of pure gold.

• 9 grams of 10K gold: 9 × 0.417 = 3.75 grams of pure gold.

• 13 grams of 18K gold: 13 × 0.75 = 9.75 grams of pure gold.

• 18 grams of 10K gold: 18 × 0.417 = 7.51 grams of pure gold.

• 36 grams of 14K gold: 36 × 0.585 = 21.06 grams of pure gold.

• 1 troy ounce of 22K gold: 31.1035 × 0.916 = 28.49 grams of pure gold.

Common Use Cases

Use the calculator to read a purity label such as 750 / 916 / 999, compare shops that quote in different scales or translate "91.6 touch" into the more familiar "22K" or "916". It can also help explain older labels, such as Russian/Soviet 583 for 14K or British 375 for 9K.

For a gold-content estimate, multiply the calculated pure-gold weight by the relevant price per unit. Keep that calculation separate from a buyer's final offer. For insurance, estate paperwork or tax declarations, check the required valuation method rather than treating a purity conversion as a complete appraisal.

How Karats Map to Color, Hardness, and Use

Karat tells you the proportion of gold, not the full alloy composition. Purity is one factor in a piece's colour, hardness and price. Common uses include:

• 24K (99.9%): used for investment bars, coins and some high-purity wedding jewellery. It is soft compared with lower-karat alloys.

• 22K (91.6%): common in wedding jewellery in South Asia and the Middle East, with a high proportion of gold.

• 18K (75%): used in fine jewellery and engagement rings.

• 14K (58.5%): common in US everyday jewellery.

• 10K (41.7%): used in items such as lower-cost chains and class rings.

• 9K (37.5%): used in the UK and several Commonwealth jewellery markets.

• White, rose, and green gold: the same purity scale applies to each. Alloy choices, including palladium / nickel for white gold, copper for rose gold and silver for green gold, affect colour. Karat alone does not identify those metals.

Calculating Purity Is Not the Same as Testing Gold

If you do not know an item's purity, ask a qualified jeweller or testing service to assess it. Professional methods include acid testing, XRF (X-ray fluorescence) and density testing. This calculator does not perform those tests or authenticate a hallmark. Once you have a measured percentage, you can use it to convert between the purity scales.

Browser-Based Processing

The calculator uses arithmetic in your browser to convert the values you enter. No Tooloogle signup or upload of calculation values is needed. You can inspect the browser's DevTools Network panel while using it to check the requests made by the page.

Related Calculations

Keep purity conversion separate from pricing and investment assumptions. The Tooloogle Discount Calculator can help with percentage discounts in a quote. The Compound Interest Calculator models compounding under the assumptions you enter; it does not predict a gold investment's return.