Metal Weight Calculator
Pick a shape and metal, enter the dimensions, and get the estimated weight in kilograms and pounds — from the volume of the section times the density of the alloy.
From a section to a weight
Every weight here is volume multiplied by density. The volume comes from the geometry of the stock — a rectangular section is simply width times thickness times length, a round bar uses the area of a circle, a tube subtracts the hollow bore, and a hex bar uses the area of a regular hexagon. Multiply that volume by the metal’s density and you have its mass.
Once you know a part’s weight, the Metal Cost Estimator turns it into a material price, and the Cut List Calculator works out how much stock a run of parts consumes.
Frequently Asked Questions
How is metal weight calculated?
Weight equals volume times density. The calculator works out the volume from the shape and dimensions you enter — for a round bar that's π/4 × diameter² × length, for a rectangular bar it's width × thickness × length — then multiplies by the density of the chosen metal. Mild steel is about 7.85 g/cm³, so a bar's weight follows directly once its volume is known.
What densities does it use for each metal?
Nominal densities in grams per cubic centimetre: mild steel 7.85, stainless steel 8.0, aluminium 2.70, copper 8.96, and brass 8.5. These are typical values — a specific alloy or grade can differ slightly, and mill tolerances on the stock change the true weight, so treat the result as a close estimate rather than a certified figure.
Which shapes are supported?
Rectangular bar, plate, and sheet (width × thickness × length); solid round bar (from its diameter); round tube (from outside diameter and wall thickness); and hex bar (from the distance across the flats). All dimensions are entered in millimetres and the length runs along the piece.
Why does my supplier's weight differ slightly?
Catalogue weights use nominal densities and nominal dimensions, but real stock varies within mill tolerance, and alloys differ from the round-number density. A difference of a percent or two is normal. For anything where weight is critical — shipping, crane picks, structural loads — weigh the actual material.
Educational estimate from nominal densities. Real alloys and mill tolerances vary — weigh the material when weight is critical.