Gold Units & Purity: The Numbers That Matter
- •1 tola = 11.6638038 grams — a fixed international reference weight, not an approximation.
- •1 sovereign / pavan = 8 grams — the standard South Indian (Kerala/Tamil Nadu) gold coin unit.
- •BIS hallmark purity: 24K = 999 (99.9% pure), 22K = 916 (91.6%), 18K = 750 (75.0%), 14K = 585 (58.5%).
- •1 tola = 12 masha = 96 ratti, so 1 masha ≈ 0.972g and 1 ratti ≈ 0.1215g.
- •Jewelers value gold by its fine gold content (weight × purity fraction), not by raw weight — a 10g 22K chain contains only 9.16g of actual pure gold.
The Real Problem This Solves
Gold measurement in India runs on units that don't match what you see on a global price ticker. Jewelers quote weight in tola or sovereign, international gold prices are quoted per troy ounce, and your own scale reads grams — none of these convert with a clean round number. On top of that, "22K gold" and "24K gold" aren't just quality labels, they represent different actual amounts of pure gold in the same weight, which is exactly what BIS hallmark purity percentages (916, 750, 585) are standardizing.
This calculator handles both problems on one page: convert between every commonly used gold weight unit, and separately convert a purity/karat value into its equivalent fine gold content and today's value, using the same fine-gold-content method jewelers actually use to price a piece.
How Purity Conversion Actually Works
Gold purity conversion isn't about the weight of metal changing, it's about how much of that weight is actual pure gold. The formula: fine gold content = weight × purity fraction, where the purity fraction comes from the BIS hallmark (999 = 0.999, 916 = 0.916, 750 = 0.750, 585 = 0.585).
Example: You have a 10-gram 22K gold chain and want to know its value against today's 24K rate. Fine gold content = 10g × 0.916 = 9.16g of pure gold. At a 24K rate of ₹14,200/gram, the chain's gold-content value is 9.16 × ₹14,200 = ₹130,072 — not 10 × ₹14,200, which would overvalue it by treating the whole weight as pure gold.
To find the equivalent weight at a different karat (e.g., "how many grams of 18K contains the same pure gold as my 10g of 22K?"), divide the fine gold content by the target purity: 9.16g ÷ 0.750 = 12.21g of 18K gold would contain the same amount of actual pure gold as 10g of 22K.
| Karat | BIS Hallmark | Purity | 10g Fine Gold Content |
|---|---|---|---|
| 24K | 999 | 99.9% | 9.99g |
| 22K | 916 | 91.6% | 9.16g |
| 18K | 750 | 75.0% | 7.50g |
| 14K | 585 | 58.5% | 5.85g |
Frequently Asked Questions
How many grams in a tola?
1 tola = 11.6638038 grams exactly — this is a fixed reference weight (180 troy grains), not a rounded approximation, and is the standard unit used in Indian gold trade and invoicing.
What is a sovereign or pavan in gold?
Sovereign (also called pavan in Kerala) is a South Indian gold coin unit equal to exactly 8 grams, commonly used in Kerala and Tamil Nadu jewelry pricing and gifting.
Why is my 22K jewelry worth less than the 24K gold rate times its weight?
Because 22K gold is only 91.6% pure — the remaining 8.4% is other metals (usually silver, copper, or zinc) added for durability. Jewelers value it by fine gold content (weight × 0.916), not by treating the full weight as pure gold.
Is 24K gold ever exactly 100% pure?
No — even 24K gold under BIS hallmarking is standardized at 999 purity (99.9%), not a full 1000, since achieving absolute chemical purity isn't practical or necessary for the hallmark standard.
What are masha and ratti used for?
These are traditional Indian sub-units, mostly seen in older jewelry invoices and rural gold trade — 12 masha make 1 tola, and 8 ratti make 1 masha. They're rarely used in modern retail billing, which has largely standardized on grams.
Does this calculator use today's live gold rate automatically?
No — enter the current 24K rate per gram yourself in the purity converter. Gold rates change daily (and even during the day), so this calculator lets you plug in whatever rate you're actually being quoted rather than relying on a number that would go stale immediately.