Gold Weight Calculator
Enter the shape and dimensions of your gold piece, choose the karat or metal, and this calculator works out the mass in grams, troy ounces and kilograms using the formula mass = volume x density. You can also enter the spot price to get an instant value estimate. Covers 8k through 24k yellow gold, sterling silver, platinum and palladium.
How to use this gold weight calculator
Select the metal and karat, then choose the shape of your piece. Enter the dimensions in millimetres - length, width and thickness for a sheet; length and wire diameter for a round wire; outer and inner diameters plus length for a tube; diameter for a spherical bead; inner ring diameter and band diameter for a ring. The calculator uses the exact geometric volume formula for each shape and multiplies by the published density of the alloy to give the mass in grams, troy ounces and kilograms. Increase the quantity field to price multiple identical pieces at once. The wastage field adds a purchasing buffer to cover metal lost during filing, polishing, soldering and casting - typically 3 to 8% for fabricated jewellery. If you enter the current spot price per troy ounce, you also get a melt-value estimate based on the pure metal content of the piece.
The gold weight formula: mass = volume x density
Every output in this calculator comes from the same two-step process. First, compute the geometric volume of the shape in cubic centimetres using the standard formulae: sheet V = l x w x t; wire/cylinder V = pi x r^2 x l; tube V = pi x (R_outer^2 - R_inner^2) x l; sphere V = 4/3 x pi x r^3; ring (torus) V = 2 x pi^2 x R x r^2 where R is the major radius and r is the minor (band) radius. Second, multiply that volume by the density of the chosen alloy (listed in the reference table above). The result is the mass in grams. Converting to troy ounces requires dividing by 31.1035 g/troy oz, the standard troy unit used by all bullion markets. Pure gold content is then mass multiplied by the purity fraction - for 18k gold that is 0.750, for 14k it is 0.583, and so on.
Gold karats, fineness and alloy density
Karat is the traditional unit for gold purity, expressed as parts per 24. Pure gold is 24k (fineness 999.9), meaning 24 out of 24 parts are gold. The most common jewellery alloys are 22k (916.7 fineness, widely used in Asian jewellery and coins), 18k (750 fineness, the European standard for fine jewellery), and 14k (585 fineness, the most popular grade in the United States). Lower-karat golds such as 10k and 9k are used where hardness and cost are priorities. The alloying metals - typically copper, silver or zinc - change the density of the final alloy. Yellow gold tends to be denser than rose gold at the same karat because of differences in the copper-to-silver ratio. The densities in this calculator use consensus published averages for each karat grade. If you know the exact density of your specific alloy, you can refine your estimate by back-calculating: the volume output gives you the geometric volume, and mass / volume gives density.
Wastage, melt value and fabrication premium
When ordering gold for jewellery fabrication, you always need to buy more metal than the finished piece will weigh. Filing, sawing, soldering, polishing and casting all remove material. Industry practice for hand-fabricated pieces is to allow 3 to 6% extra; casting operations may run 5 to 10% because of sprue and runner waste. The melt value shown by this calculator is the intrinsic bullion value of the pure metal content at the spot price you enter - it does not include the refiner's spread, fabrication charges, or the retail markup on finished jewellery. Retail prices for fine jewellery are typically 1.5 to 4 times the melt value, depending on design complexity, brand and market.
Gold karat, fineness and density reference
| Karat | Fineness | Purity (%) | Density (g/cm³) |
|---|---|---|---|
| 24k | 999.9 | 99.99 | 19.3 |
| 22k | 917 | 91.67 | 17.85 |
| 21k | 875 | 87.50 | 17.15 |
| 18k | 750 | 75.00 | 15.58 |
| 14k | 585 | 58.33 | 13.07 |
| 10k | 417 | 41.67 | 11.57 |
| 9k | 375 | 37.50 | 11.22 |
| 8k | 333 | 33.33 | 10.9 |
| Silver (fine) | 999 | 100 | 10.49 |
| Platinum | - | 100 | 21.45 |
| Palladium | - | 100 | 12.02 |
Density values are published averages for standard alloy blends. Pure gold content is the fraction of fine (24k) gold by mass.
Frequently asked questions
How do I calculate the weight of a gold ring?
Select "Ring (torus)" from the shape dropdown and enter the inner diameter of the ring and the diameter of the band cross-section in millimetres. The calculator applies the torus volume formula V = 2 x pi^2 x R x r^2, where R is the major radius (half the sum of the inner diameter and the wire diameter) and r is the minor radius (half the wire diameter), then multiplies by the density of your chosen karat. A standard US size 7 ring (inner diameter about 17.3 mm) in 2.5 mm round-wire 18k gold weighs roughly 3.5 g.
What is the density of 18k gold?
18k (750 fineness) yellow gold has a density of approximately 15.58 g/cm3. The exact value varies slightly depending on the alloying metals used: rose gold (which contains more copper) can reach 15.9 g/cm3, while white gold (alloyed with palladium or nickel) typically falls between 15.1 and 16.4 g/cm3. For most jewellery estimation purposes, 15.58 g/cm3 is the standard reference value.
What is the difference between a troy ounce and a regular ounce?
A troy ounce is 31.1035 grams, while a standard avoirdupois ounce (used for everyday goods) is 28.3495 grams. All precious metals - gold, silver, platinum, palladium - are traded internationally in troy ounces. When you see a gold spot price quoted as "USD per ounce", it is always the troy ounce. This calculator converts your grams result to troy ounces automatically.
How is the melt value different from the retail price?
The melt value is the intrinsic worth of the pure metal in your piece at the current spot price - what a refiner would theoretically pay if they melted it down. It is calculated from the pure gold (or silver/platinum) content multiplied by the spot price per troy ounce. Retail jewellery prices are higher because they include design, labour, overhead, profit margin, and brand premium. Scrap dealers also pay below the melt value to cover refining costs, so expect a buyback price of 70 to 95% of melt depending on the buyer.
What wastage percentage should I use?
For hand-fabricated sheet and wire work, 3 to 5% is typical. For lost-wax casting, 5 to 10% accounts for sprue metal and surface finishing. Complex pieces with lots of soldering and filing may need 8% or more. If you are a professional and know your shop's exact recovery rate from previous jobs, use that figure instead. For a quick purchase estimate, 5% is a reasonable default.
Can I use this for silver, platinum or palladium?
Yes. Select the relevant metal from the "Metal / Karat" dropdown. The calculator uses the published density for each pure metal: silver 10.49 g/cm3, platinum 21.45 g/cm3 and palladium 12.02 g/cm3. For the melt value, enter the spot price per troy ounce for that metal. Note that the "pure gold content" output is set to zero for non-gold metals.