Metal Weight Calculator
Calculate metal weight from dimensions and density. Supports round, square, hex bars, sheet, pipe, and profiles with instant unit conversion.
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What the metal weight calculator does
Metal is bought, shipped, and priced by weight, but you measure it by size, so the two have to be connected. This does that. You pick the shape, choose the metal and enter its density, give the dimensions and a quantity, and it returns the weight of one piece and of the whole lot.
It covers the common stock shapes, from plain bars to structural profiles. Below is how it works and the one input that decides the answer.
How to use it
- Pick the shape from the type list, such as round bar, sheet, tube, or a profile.
- Choose the metal and enter its density in grams per cubic centimeter, and a quantity.
- Enter the dimensions for that shape, each with its unit, then press Calculate, or Reset to clear it.
How the weight is worked out
Weight is volume times density, which is the whole idea behind the calculator:
Weight = volume × density
It works out the volume of metal from the shape and its dimensions, then multiplies by the density of the metal to get the weight of one piece. Multiply by the quantity and you have the weight of the batch. Getting the volume right is geometry; getting the weight right needs the density.
Density is the key input
The density is what turns a size into a weight, and it is the input that decides the result, because the same shape in different metals weighs very differently. A bar of aluminium and the same bar in steel are worlds apart in the hand, and the gap is all in the density: steel is about three times as heavy as aluminium for the same volume.
So enter the density of the metal you are actually using. As a guide, steel is around 7.85 grams per cubic centimeter, stainless steel a little more at about 8.0, aluminium about 2.70, copper about 8.96, brass about 8.5, and titanium about 4.51. Picking your metal from the list points you to which one you mean, but the density figure is the one the weight rides on, so set it to match your stock.
The shapes it handles
The shapes cover the forms metal stock comes in, and each has its own volume formula. The simple ones are a round bar, worked as a cylinder, a square or rectangular bar, and a flat sheet, which are just their dimensions multiplied together.
Then there are the hollow and structural shapes. A tube is worked as the metal between an outer and an inner circle, so its wall thickness matters. The profiles, the box, L, U, I or H, and T sections, are the beams and angles of structural steel, and each is worked out from the area of its cross-section run along its length. Pick the shape that matches your stock and the right volume formula is used, so a length of angle and a sheet of plate are each measured correctly.
A worked example: a steel round bar
Say you have a steel round bar 2 centimeters across and 1 meter long, with steel's density of about 7.85 grams per cubic centimeter.
The bar is a cylinder, so its volume is pi times the radius squared times the length: π × 1² × 100 = about 314 cubic centimeters. Times the density, that is 314 × 7.85 = about 2,466 grams, or roughly 2.47 kilograms.
The same bar in aluminium, at about 2.70, would weigh nearer 0.85 kilograms, which is the density doing the work.
Questions people ask
How do I calculate the weight of metal?
Work out the volume from the shape and dimensions, then multiply by the metal's density. A steel bar 2 centimeters across and 1 meter long weighs about 2.47 kilograms.
What density should I use?
The density of your metal, in grams per cubic centimeter. Steel is about 7.85, aluminium about 2.70, copper about 8.96. Enter the one for your stock.
How is a tube worked out?
As the metal between the outer and inner circles, so the wall thickness counts. A thicker wall means more metal and more weight.
Why does the metal matter so much?
Because density varies widely between metals. The same shape in steel weighs about three times what it does in aluminium.
References
A quick note on the numbers. The weight is volume times density, with the volume coming from the geometry of each shape. The density values quoted, such as about 7.85 for steel and 2.70 for aluminium, are the standard published densities of those metals, widely tabulated in engineering references. The unit conversions follow the US National Institute of Standards and Technology guide.
- National Institute of Standards and Technology (NIST), Special Publication 811, Guide for the Use of the International System of Units (SI). https://www.nist.gov/pml/special-publication-811
Mahendra Thapaliya is a graduate student in Structural Engineering at the University of Bologna, with research interests in structural systems, FEM, earthquake engineering, and numerical modeling. At Eon Tools, he reviews construction tools.