Use this gold weight and purity calculator to find out how much pure gold is actually in a piece of gold. A ring, a coin, a bangle or a bar is rarely pure gold: most gold items are an alloy, a mixture of gold and other metals, and the weight on the scale is the weight of the whole mixture, not the weight of the gold in it. Enter the weight, choose the unit it was weighed in, and choose the karat, and this calculator shows the fine gold weight — the pure gold content — in grams, in tola and in troy ounces, together with the purity as a percentage and the fineness. It gives you a weight, not a price: no live price, no buyer discount and no making charges are involved, so the result is the same whatever the market is doing on the day.
That distinction matters whenever you buy, sell or inherit gold. Two pieces can weigh exactly the same and contain very different amounts of gold. A 10-gram piece of 22K gold contains 9.1667 grams of pure gold. A 10-gram piece of 18K gold contains only 7.5000 grams. The difference is the alloy — the copper, silver, zinc or other metals mixed in to make the gold harder, change its colour, or bring its price down. Jewellers, refiners and scrap buyers all work on the pure-gold content, because that is the part that has the metal value. Knowing it before you negotiate means you are comparing the same thing, instead of comparing total weights that hide different purities.
Why weight alone does not tell you the gold content
Karat is the measure of purity. Pure gold is 24 karat, which is 100% gold. 22K gold is 22 parts gold out of 24, or 91.67% pure. 21K is 87.50% pure, 18K is 75.00% pure, and 14K is 58.33% pure. The rest is alloy. Alloy is not a defect: pure gold is soft and scratches and bends easily, so a little alloy makes jewellery wearable, and different alloys give gold its yellow, white or rose colour. But alloy adds weight without adding gold, which is why a heavy piece can still hold less gold than a lighter piece of higher karat.
The same point applies to hallmarks and stamps. A stamp that says 22K, 916, 21K or 875 is a claim about purity, and this calculator takes that claim at face value. It cannot test the metal. If a piece is unmarked, worn, plated or of unknown origin, have it assayed or tested by a reputable jeweller or refiner before you rely on any figure. Stones, clasps, springs and other non-gold parts also add weight, so weigh the gold part only where that is possible, or treat the result as an upper estimate.
How the calculation works
The calculation has two steps. First, the weight is converted to grams, using fixed weight factors: one tola equals 11.6638 grams, one troy ounce equals 31.1034768 grams, and one kilogram equals 1,000 grams. One gram is the base unit, so a weight given in grams needs no conversion. Second, the pure gold is the weight in grams multiplied by the karat fraction: pure gold = grams × karat ÷ 24. The purity percentage is karat ÷ 24 × 100, and the fineness is karat ÷ 24 × 1,000 — fineness is the same purity expressed in parts per thousand, which is how refiners and many hallmarks state it. 24K gold is 999 fineness, 22K is 917, 21K is 875, 18K is 750 and 14K is 583.
The results are shown to four decimal places for the weights, because small differences matter when gold is weighed: 0.0001 grams is a tenth of a milligram, and refiners routinely work to that precision. The purity is shown to two decimal places, and the fineness as a whole number. Nothing is rounded before the final display, so converting the result back to the original unit returns the weight you entered, apart from the last displayed digit.
How to use this calculator
- Enter the weight of the gold item in the first field. Use the weight exactly as it was measured, without stones or packaging where possible.
- Choose the unit that weight is in: grams, tola, troy ounces or kilograms. If your scale reads in grams, choose Grams.
- Choose the karat of the gold: 24K, 22K, 21K, 18K or 14K. Use the hallmark on the piece, or the karat stated on its certificate.
- Press Calculate. The results show the pure gold weight in grams, tola and troy ounces, plus the purity percentage and the fineness.
Worked example
Suppose you have a bangle that weighs 10 grams and is stamped 22K. Enter 10, choose Grams, choose 22K, and press Calculate. The weight in grams is 10, and the pure gold is 10 × 22 ÷ 24 = 9.1667 grams. In tola that is 9.1667 ÷ 11.6638 = 0.7859 tola, and in troy ounces it is 9.1667 ÷ 31.1034768 = 0.2947 troy ounces. The purity is 91.67% and the fineness is 917. The remaining 0.8333 grams is alloy.
Try the same check with a tola weight before you sell. A chain that weighs 2 tola and is 18K gold weighs 2 × 11.6638 = 23.3276 grams in total, and its pure gold is 23.3276 × 18 ÷ 24 = 17.4957 grams — exactly 1.5000 tola of pure gold, or 0.5625 troy ounces, at 75.00% purity and 750 fineness. If a buyer quotes you for 2 tola of 18K gold as if it were 2 tola of pure gold, the pure-weight figures show at once that a quarter of the weight is alloy, not gold.
What this calculator does not do
This calculator gives weights only. It does not fetch a live gold price, it does not work out a money value, and it does not apply a buyer discount, refining deduction, making charge or tax. That is deliberate: the pure-gold weight is a fact about the metal, while its money value changes with the market and with who is buying. To turn the pure weight into a value, multiply it by the price per gram for pure gold on the day, then deduct whatever the buyer charges — the Scrap Gold Calculator does that calculation, using the live price per gram and a buyer discount you enter. Use this page first to establish the weight, and the scrap calculator second to establish the value, so that a disagreement about price never hides a disagreement about weight.
It also does not judge whether a piece is genuine, whether its hallmark is accurate, or whether it is worth more as jewellery than as metal. A well-made or antique piece can be worth more intact than its gold content alone, and melting or selling it for scrap cannot be undone. If the piece may have craftsmanship, brand or collector value, get a separate valuation before you treat it as scrap.
All Tools · Gold Weight Converter · 22K to 24K Gold Price Converter · Gold Rate Per Gram Calculator · Scrap Gold Calculator
Frequently Asked Questions
How do I work out the pure gold in a piece of jewellery?
Weigh the piece, find its karat, and multiply the weight in grams by the karat divided by 24. For example, 10 grams of 22K gold holds 10 × 22 ÷ 24 = 9.1667 grams of pure gold. This calculator does the same arithmetic and also converts the result into tola and troy ounces.
What is the difference between pure gold weight and total weight?
Total weight is the weight of the whole alloy — gold plus the other metals mixed in. Pure gold weight, also called fine weight, is only the gold part. For 24K gold the two are the same. For any lower karat, the pure weight is smaller, and the gap grows as the karat falls.
How many grams of pure gold are in 10 grams of 22K gold?
9.1667 grams. That is 0.7859 tola or 0.2947 troy ounces of pure gold, at 91.67% purity and 917 fineness. The remaining 0.8333 grams is alloy.
Does this calculator give me a money value for my gold?
No. It gives weights only, with no live price and no buyer discount. To get a money value, take the pure weight from this calculator and use the Scrap Gold Calculator, which applies the live price per gram and a buyer discount.
What is fineness, and how is it different from karat?
Fineness and karat are two scales for the same purity. Karat counts parts of gold out of 24, while fineness counts parts out of 1,000. So 24K is 999 fineness, 22K is 917, 21K is 875, 18K is 750 and 14K is 583. Hallmarks often show the fineness number rather than the karat.
Is a tola the same as a troy ounce?
No. One tola equals 11.6638 grams and one troy ounce equals 31.1034768 grams, so one troy ounce is about 2.6667 tola. Neither is the regular (avoirdupois) ounce of 28.3495 grams, which is not used for gold.
Should I use this calculator before I sell scrap gold?
Yes. Establish the pure-gold weight first, so you can check the buyer’s arithmetic and spot any confusion between total weight and pure weight. If the karat is unknown or the piece is unmarked, have it tested first, and consider whether it has craftsmanship or collector value before selling it as scrap.