Material Weight Calculator
Work out the weight of semi-finished products and cut pieces from their dimensions: pick a profile, enter the measurements, choose a material or your own density. The calculator returns cross-sectional area, volume, mass, mass per metre and the total mass of a quantity – live with every input and exportable as a cutting list.
Weight Calculator
Geometric mass calculation m = V·rho from a constant cross-sectional area and length. Corner radii and chamfers are ignored; the density is a reference value. For billing-relevant masses use the actual weighing or the manufacturer's figure.
Results
Calculating …
Formulas and fundamentals
Weight follows geometrically from volume and density: m = V·rho. The volume of a prismatic semi-finished product is the product of the constant cross-sectional area A and the length l, so V = A·l. In practice the calculator works in mm and g/cm³: a mass in kilograms is m = A[mm²]·l[mm]·rho[g/cm³]/10⁶, and the mass per metre is m' = A[mm²]·rho[g/cm³]/1000. The mass per metre is independent of length and serves as a catalogue value for bar stock.
The cross-sectional area is determined exactly for each profile: round bar A = π/4·d², tube as an annulus A = π/4·(D²−d²), square A = a², sheet and flat bar as a rectangle A = b·t, hexagon via the width across flats SW with A = (√3/2)·SW², and angle as two legs minus the corner counted once, A = t·(a + b − t). For composite profiles (tube, angle) the cut-out is subtracted cleanly so that no area is counted twice.
Density is the decisive material-dependent factor. Common reference values in g/cm³ are steel 7.85, stainless 7.90, grey cast iron 7.2, aluminium 2.70, brass 8.50, copper 8.90, bronze 8.8 and titanium 4.5. Aluminium therefore weighs only about a third of steel for the same volume. For exact evidence use the density stated by the stock supplier; the calculator allows a free density entry for this.
Worked example
A steel sheet 1000 × 2000 mm and 10 mm thick has the volume V = 1000·2000·10 = 2·10⁷ mm³ = 0.02 m³. With the steel density 7.85 g/cm³ the mass is m = 0.02 m³ · 7850 kg/m³ = 157 kg.
A steel round bar 50 mm in diameter and 1000 mm long has the cross-sectional area A = π/4·50² = 1963.5 mm². This gives the mass m = 1963.5·1000·7.85/10⁶ = 15.41 kg and at the same time the mass per metre of 15.41 kg/m.
The same round bar in aluminium (2.70 g/cm³) weighs only m = 1963.5·1000·2.70/10⁶ = 5.30 kg – about a third of the steel weight. If 10 such bars are needed, the total mass is 53.0 kg; the calculator reports single and total mass separately.
Frequently asked questions
Which density should I use for steel?
For unalloyed and low-alloy structural steel, 7.85 g/cm³ is the usual value. Stainless austenitic steel is somewhat higher at around 7.90 to 8.00 g/cm³, grey cast iron lower at 7.1 to 7.3 g/cm³. For exact figures always refer to the supplier's data sheet; the calculator allows a free density entry.
What does mass per metre mean and why is it useful?
The mass per metre (kg/m) is the weight of one metre of bar stock and depends only on the cross-section and density, not on the length you enter. It matches the per-metre weights in material catalogues and is handy for quickly estimating the mass of any length or for checking catalogue values.
How is the weight of a hexagon calculated?
The governing dimension is the width across flats SW, the distance between the parallel faces. The cross-sectional area of a regular hexagon is A = (√3/2)·SW² ≈ 0.866·SW². For the same width across flats the hexagon is therefore lighter than a square of equal side length and heavier than the inscribed round bar.
Does the calculation also work for tubes and angles?
Yes. For a tube the annulus A = π/4·(D²−d²) is formed from the outer and inner diameter. For an angle (L-profile) both legs are counted and the shared corner is subtracted once: A = t·(a + b − t). Corner radii on the inner edges are ignored, which puts the result slightly on the safe (heavier) side.
Why do my weighed values differ slightly?
Real semi-finished products have dimensional and rolling tolerances and a scattering density; corner radii and chamfers are also ignored in the parametric calculation. Deviations of a few per cent are normal. For billing-relevant masses use the actual weighing or the manufacturer's figure.
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