Quick Answer
Gold melt value = weight in grams x (karat / 24) x (spot price / 31.1034768). A karat is one 24th of the alloy by weight, so 14K is 58.33% gold and 18K is exactly 75%. Ten grams of 14K contains 5.833 grams of fine gold. Gold filled stock is valued from its stamped weight fraction instead.
Every gold valuation is the same three numbers multiplied together: how much the piece weighs, how much of that weight is actually gold, and what gold is trading at. The calculator above runs that chain in either direction the trade uses it — solid karat gold, or gold-filled stock where the gold is a stamped fraction of the total weight. It asks you for the spot price rather than supplying one, and that is deliberate: a price printed into a page in 2026 is wrong by the afternoon.
How Karat Gold Value Is Calculated
Gold is quoted per troy ounce of fine gold — pure metal. Your ring is not pure metal, so the first job is to convert the quoted price into a price per gram, and the second is to work out what share of the ring is gold.
The whole calculation. melt value = weight in grams × (karat / 24) × (spot price / 31.1034768). The last bracket turns a price per troy ounce into a price per gram; the middle one is the definition of a karat.
A karat is one twenty-fourth of the alloy by weight. That is not a rule of thumb, it is what the word means: 18K gold is 18 parts gold to 6 parts everything else, so 18/24 = 75% of its weight is gold. Multiply the spot price by that fraction and you have what a gram of that alloy is worth as metal.
Because purity is a pure ratio, the second column below never changes with the market. Whatever gold does this week, 14K is worth 58.33% of it and 10K is worth 41.67% of it.
| Karat | Ratio | Gold by weight | Worth this share of spot | Usual stamp |
|---|---|---|---|---|
| 24K | 24/24 | 100% | 100.00% | 999 |
| 22K | 22/24 | 91.67% | 91.67% | 916 |
| 21K | 21/24 | 87.50% | 87.50% | 875 |
| 18K | 18/24 | 75.00% | 75.00% | 750 |
| 14K | 14/24 | 58.33% | 58.33% | 585 |
| 10K | 10/24 | 41.67% | 41.67% | 417 |
| 9K | 9/24 | 37.50% | 37.50% | 375 |
Read the last two columns against each other and four of the seven rows stop agreeing with themselves, in both directions. Two stamps sit slightly above the ratio: 585 against 14/24 = 58.3333%, and 417 against 10/24 = 41.6667%. Those are legal minimums from a different system, not roundings of the karat. Two sit slightly below it: 999, because refined gold is never quite 100%, and 916 against 22/24 = 91.6667%. Only three — 875, 750 and 375 — land exactly on the ratio.
The gaps are small, and only the two that sit above the ratio can make an answer come out higher than the metal really is. 585 is 0.2857% more gold than 14/24; 417 is 0.08% more than 10/24. That is a rounding error on a chain and a real number on a bar.
Which number should you use? If your piece is stamped 14K, use the karat. If it is stamped 585, choose “Enter fineness” and type 585. The gap is 0.2857% — small enough to ignore on a chain, large enough to notice on a kilo bar. The calculator prints which purity it used underneath the answer so the two can never quietly disagree.
Gold Is Priced in Troy Ounces, Not Ounces
This is the mistake that costs the most and is the easiest to make. The ounce gold is priced in is the troy ounce of 31.1034768 grams. The ounce your kitchen scale reads is the avoirdupois ounce of 28.349523125 grams. A troy ounce is 9.71% heavier, so treating one as the other overstates a valuation by that much.
The trade also weighs in pennyweights, and much of South Asia weighs in tolas. All of them are fixed multiples of the same grain, published by the NIST Office of Weights and Measures conversion table for precious metal sales.
| Unit | Grams | In one troy ounce | Where you meet it |
|---|---|---|---|
| Troy ounce (oz t) | 31.1034768 | 1 | Every published gold price |
| Gram (g) | 1 | 31.103477 | Jewellers outside the US |
| Pennyweight (dwt) | 1.55517384 | 20 | US scrap and dental buyers |
| Tola | 11.6638038 | 2.666667 | India, Pakistan, the Gulf |
| Ounce, avoirdupois (oz) | 28.349523125 | 1.097143 | Kitchen and postal scales |
| Kilogram (kg) | 1000 | 0.031103 | Bars and bulk lots |
A pennyweight is exactly a twentieth of a troy ounce, which is why US buyers can quote a price per dwt by dividing the spot price by 20 in their heads. A tola is 180 grains, or three eighths of a troy ounce — 11.6638038 grams. Both fall straight out of the same table rather than being local conventions that need looking up separately.
How to Use the Gold Karat Value Calculator
- Find today’s gold price.
Any published quote works — the calculator does not care which currency it is in, and every figure it returns comes back in that same currency. Type the number and pick the unit it was quoted in. Most quotes are per troy ounce.
- Weigh the piece and pick the matching unit.
Take off anything that is not metal first: stones, clasps of a different alloy, leather, enamel. Those are weight you will not be paid for. If your scale reads in ounces, check whether they are troy ounces before choosing the unit.
- Choose the karat, or enter the fineness.
Use the karat mark if the piece carries one. If it carries a three-digit number instead — 585, 750, 916 — choose “Enter fineness” and type it. An unmarked piece has to be tested; there is no way to read purity off a photograph.
- Read the melt value, then the line beneath it.
The headline figure is the metal content. The panel also shows the fine gold in grams, the value of one gram of your alloy, and the exact purity used, so you can check each step rather than trusting the total.
- Add a buyer’s offer if you have been quoted one.
Enter the percentage of melt you were offered and the last cell shows what that comes to. Leave it blank and the row stays empty — the calculator will not invent a dealer margin for you.
Worked Example: 10 Grams of 14K
Suppose gold is quoted at 2,400 per troy ounce. That figure is only here to make the arithmetic visible — put your own in the calculator.
- Turn the ounce price into a gram price.
2,400 ÷ 31.1034768 = 77.16 per gram of fine gold.
- Take the purity.
14K is 14/24 = 0.583333, so 58.33% of the piece is gold.
- Value one gram of the alloy.
77.16 × 0.583333 = 45.01. That is what a gram of 14K is worth as metal.
- Multiply by the weight.
45.01 × 10 = 450.11. The piece contains 5.833 grams of fine gold.
Run the same piece as a 585 stamp instead of 14/24 and the answer is 451.40 — 1.29 more on ten grams. On a hundred grams that gap is nearly 13, which is why the calculator names the purity it used instead of leaving you to guess.
If you are working out zakat rather than resale value, the number that matters is the fine gold figure, not the melt value; the Zakat Calculator works from the gold you actually hold.
Gold Filled Is a Different Calculation
Gold-filled stock is a layer of karat gold mechanically bonded to a base-metal core, and it is quoted as a fraction of the whole article’s metal weight. A piece stamped 1/20 12K GF is telling you two separate things: a twentieth of its weight is the gold layer, and that layer is 12 karat. You need both, because only 12/24 of that twentieth is gold.
The threshold is not a trade convention, it is a marking rule. The FTC’s Guides for the Jewelry, Precious Metals, and Pewter Industries at 16 CFR 23.3 put it plainly: “When such plating constitutes at least 1/20th of the weight of the metal in the entire article, the term ‘Gold Filled’ may be used.” Below a twentieth the same piece is Rolled Gold Plate or Gold Overlay, and the fraction has to be stamped — the Guides give “1/40th 12 Kt. Rolled Gold Plate” as an example. The calculator applies that test to whatever fraction you pick and tells you which side of it you are on.
The arithmetic is worth seeing once. Ten grams of 1/20 12K gold filled, at the same 2,400 per troy ounce:
- The layer is a twentieth of the weight.
10 × 1/20 = 0.5 grams of 12K gold.
- Half of that layer is gold.
0.5 × 12/24 = 0.25 grams of fine gold — a fortieth of the whole piece.
- Value the fine gold.
0.25 × 77.16 = 19.29.
The identical piece in solid 12K would hold 385.81 of gold. That factor of twenty is the entire point of gold-filled stock, and it is why a jewellery box of gold-filled chain is worth far less than its weight suggests.
Gold filled is not gold plated. Electroplating deposits a layer measured in microns, not in a fraction of the article’s weight, and it carries no stamped fraction at all. If your piece says GP, GEP, HGE or nothing, this mode will overstate it by a wide margin. Only use it on a piece that carries a fraction in front of the karat mark.
Why a Buyer’s Offer Sits Below Melt
Melt value is what the metal in the piece contains. It is not a price anybody is obliged to pay, and no honest calculator can tell you what you will be offered. A buyer has to test the purity, refine the metal, carry the price risk between buying and selling, and make a margin. Every one of those comes out of the same lump.
NIST puts the same point in one line in its conversion table for precious metal sales: prices offered “usually reflect reductions based on an item’s gold ‘karat’ content and deductions for other factors.” So compare offers as a percentage of melt rather than as absolute numbers — that is the only way two quotes made on different days are comparable at all. Enter the percentage in the calculator to see it in money, or use the Reverse Percentage Calculator to work out what share of melt a quote you have already been given actually represents.
One thing melt value deliberately ignores: whether the piece is worth more intact. Melt is a floor, not a ceiling. A hallmarked antique, a signed designer piece or a collectable coin can be worth a multiple of its metal, and a calculator that only knows weight and purity cannot see any of that.
Mistakes That Change the Answer
- Weighing in the wrong ounce.
The troy ounce is 9.71% heavier than the ordinary ounce. Enter avoirdupois ounces as troy and the answer comes out too high by that margin. The calculator warns you when the avoirdupois ounce is selected, because it is almost never what a gold scale means.
- Weighing the stones.
Gemstones, pearls and enamel all sit on the scale and none of them are gold. A stone-set ring weighed whole can read a third heavier than its metal. Weigh the mount alone, or accept that the figure is an upper bound.
- Treating a plated piece as filled.
Plated jewellery carries a gold layer thousands of times lighter than gold-filled stock. Without a stamped fraction, the gold-filled mode has nothing real to work from.
- Reading 24K as exactly pure.
The calculator treats 24K as 24/24 because that is the definition, but NIST describes an item marked 24k as 99.9% pure rather than 100%. A 24K figure is therefore a ceiling, about a tenth of a percent above what an assay will find.
- Expecting melt to be an offer.
It is the metal content and nothing else. Refining costs, assay costs and the buyer’s margin all come out of it before anyone hands over money.
Gold Karat Value Calculator: FAQ
Exactly 58.33% of whatever a gram of pure gold is worth, because 14K is 14 parts gold in 24. To get the money figure, divide the spot price per troy ounce by 31.1034768 to reach a price per gram of fine gold, then multiply by 0.583333. At a spot price of 2,400 per troy ounce that is 45.01 per gram of 14K — but the ratio is the durable part of the answer and the price is not.
Ten grams of 14K contains 5.833 grams of fine gold, whatever the market is doing. Multiply that by the current price per gram of fine gold and you have the melt value — at 2,400 per troy ounce it works out at 450.11. Enter your own spot price in the calculator above rather than relying on any figure written into a page, including this one.
As metal, yes, exactly. 18/24 = 0.75, and the 750 stamp used in Europe is the same number rather than a rounding of it, so 18K is one of the karats where the ratio and the stamp agree perfectly. What you are offered for 18K will be below 75% of spot, because the buyer’s costs and margin come off the melt value.
585 means 585 parts gold per thousand, or 58.5%. 14K means 14 parts in 24, which is 58.3333%. The stamp is slightly higher, by 0.2857% in relative terms — on ten grams at 2,400 per troy ounce, 451.40 against 450.11. Both are legitimate marks; they come from different systems. Use whichever your piece actually carries, and the calculator will print the purity it applied.
Because melt value is the metal in the piece, not a price. The buyer has to assay it, refine it, carry the price risk until the refined metal is sold, and earn something for doing it. NIST notes the same thing about the trade: offered prices reflect deductions for an item’s karat content and other factors. Compare quotes as a percentage of melt so that offers made on different days can be compared at all.
A twentieth of the weight is the gold layer, and half of that layer is gold, so a fortieth of the whole piece is fine gold. Ten grams of 1/20 12K gold filled therefore holds 0.25 grams of fine gold — about 19.29 at a spot price of 2,400 per troy ounce, against 385.81 if the same piece were solid 12K. Many refiners set a minimum lot size before they will take gold-filled scrap at all.
For a rough figure, yes, if it reads in grams and resolves to at least 0.1 g. What you must not do is read its ounces as troy ounces: a kitchen scale weighs in avoirdupois ounces of 28.3495 g, and gold is priced per troy ounce of 31.1035 g. Set the scale to grams and choose grams in the calculator, and the ambiguity disappears.
The tola is the bullion weight used across India, Pakistan and the Gulf. It is 180 grains, which is three eighths of a troy ounce, or 11.6638038 grams — so a troy ounce is 2.666667 tolas. It is a fixed multiple of the same grain the troy ounce is built from, not a separate local standard, which is why a price per tola converts exactly rather than approximately.
