Metal weight calculator
Calculate how much a piece of metal weighs from its shape, dimensions and material — handy for quoting a job, planning a cut or checking shipping. Enter a price per kilo to get the stock cost too.
How the weight is calculated
Weight is simply volume × density. This tool works out the volume from the shape you pick and the dimensions you enter (in millimetres), then multiplies by the material's density to give the weight — and, if you add a price per kilo, the cost of the stock. The densities are the standard values for common engineering metals; choose "Custom density" to type your own for a specific alloy or a plastic. It is ideal for quoting a job, planning how much bar to buy, or checking a shipping weight — all before a single chip is cut. Everything is calculated in your browser.
Which dimensions do I enter?
It depends on the shape. A round bar needs its diameter and length; a tube needs the outer and inner diameters plus length; a plate needs width, length and thickness; a hex bar needs the across-flats size and length. Everything is in millimetres.
Where do the densities come from?
They are the standard published densities for common engineering metals. Real alloys vary a little — a particular stainless or aluminium grade can differ by a couple of percent — so for a precise figure, look up your grade's density and enter it under "Custom density".
Can I use a material that's not in the list?
Yes. Pick "Custom density" and type the density in g/cm³ — for example a titanium alloy, a bronze grade, or a plastic like POM at about 1.42. Any material works as long as you know its density.
How accurate is the result?
It is the theoretical weight from the nominal dimensions you enter. Real stock varies with dimensional tolerances, mill scale and the exact alloy, so treat the answer as a close estimate — plenty accurate for quoting, cutting plans and shipping, but not a substitute for a scale on a certified part.
Hex bar — across flats or across corners?
Across flats — the distance between two opposite faces, which is the size a spanner reads and how hex stock is sold. That is what the "Across flats" box expects.
Using the number in practice
A weight is rarely the answer on its own — it is the input to a decision. It tells you what a finished part costs to post, whether a fabrication can be lifted by one person or needs a crane, how much bar to buy for a batch, and what the raw material is worth before a single chip is cut. Working it out before you order is also the cheapest quality check there is: if the calculated weight is far from what the supplier's certificate says, something about the dimensions or the grade is not what you think it is.
Quoting and buying stock
For a quote, calculate the weight of the stock rather than of the finished part — you pay for the bar you buy, including everything the machine turns into swarf. Add the length lost to parting off and clamping, put in the price per kilo, and you have a material cost you can defend. For a batch, multiply by the quantity and compare the total against the standard lengths your supplier sells: buying one length longer is often cheaper than ordering a short special.
Why a tube saves more than it looks
Stiffness comes overwhelmingly from the material furthest from the centre, so a tube keeps most of the strength of a solid bar while losing a great deal of the weight. Compare the two here — a 50 mm solid steel bar one metre long against a 50 mm tube with a 40 mm bore — and the difference is one you can feel in the hand and see in the price. That is why frames, handles and structures are hollow, and this is the quickest way to put a number on it before you commit.
