Calculate the weight of a metal bar, plate, or sheet from its dimensions and material — steel, aluminum, copper, brass, iron, or stainless.
weight = length × width × thickness × density
Weight is the volume in cubic inches times the material's density. Steel is 0.2836 lb/in³, aluminum 0.0975, copper 0.3230.
Aluminum is about a third the weight of steel for the same size — always pick the right material.
A 12 x 12 x 0.25 inch plate is 36 cubic inches. In steel (0.2836 lb/in³) it weighs 36 x 0.2836 = 10.2 lb. The identical plate in aluminum (0.0975 lb/in³) weighs only 3.5 lb — about a third — which is exactly why aluminum is chosen where weight matters.
For shipping, fabrication, or structural load, knowing the weight up front prevents surprises. Multiply by the number of pieces for a batch: ten of those steel plates is 102 lb.
Densities are standard engineering-handbook values for common metals. Alloy variations shift these slightly.
Metal weight is volume times density. Get the volume for the profile — a round bar is pi times radius squared times length, a plate is width times thickness times length, a hex bar is 0.866 times width squared times length — then multiply by the metal's density. The one trap is tubes and pipe: subtract the hollow bore, since only the metal wall has weight.
Density is fixed by the material: carbon steel about 0.284 lb/in³, aluminum about 0.098, stainless about 0.289, copper about 0.323. Using steel's density for an aluminum part is a common and large error. For sheet metal, thickness is often given as a gauge number, and the same gauge means different thicknesses for different metals — convert gauge to actual thickness for your metal before calculating.
A 12×12×0.25″ steel plate weighs about 10.2 lb — 36 in³ at 0.2836 lb/in³.
Find the volume from the shape (for a round bar, pi times radius squared times length) and multiply by the metal's density, about 0.284 lb/in³ for steel or 0.098 for aluminum.
Calculate the outer volume and subtract the inner (bore) volume, since only the metal wall has weight, then multiply the difference by the metal's density.
No. The same gauge number means different thicknesses for steel, stainless, and aluminum, so always convert gauge to actual thickness using the chart for your specific metal.