Metal Weight Calculator — Steel, Stainless & Aluminium (kg)
Work out the weight of steel, stainless steel and aluminium — plate, sheet, bar, tube, box section and angle — in kilograms. Pick the material and shape, enter the dimensions in millimetres, and the calculator returns the weight per piece and total, using standard published metal densities.
Metal Weight Calculator
Metal densities used
The calculator uses these standard published densities. Real weight varies slightly with the exact alloy and rolling tolerance.
| Material | Density (kg/m³) |
|---|---|
| Mild steel | 7,850 |
| Galvanised steel | 7,850 |
| Stainless steel 304 | 7,930 |
| Stainless steel 316 | 7,980 |
| Aluminium | 2,710 |
| Brass | 8,500 |
| Copper | 8,940 |
How metal weight is calculated
Weight is simply volume × density. Work out the volume in cubic metres, then multiply by the material density:
- Plate / sheet: length × width × thickness × density
- Round bar: π/4 × diameter² × length × density
- Flat / square bar: cross-section area × length × density
- Tube & box: (outer area − inner bore area) × length × density
- Angle: (leg A + leg B − thickness) × thickness × length × density
For example, a 1m × 1m × 10mm mild steel plate is 1 × 1 × 0.01 = 0.01m³ × 7,850 kg/m³ = 78.5 kg. An 8ft × 4ft (2440 × 1220mm) mild steel sheet weighs about 23kg per millimetre of thickness — so roughly 70kg at 3mm.
Buy metal sheet, plate & sections
Rackerman supplies mild steel sheet, steel plate, galvanised, stainless and aluminium sheet in standard UK sizes (8x4, 2m x 1m and larger — sheet is supplied in full sheets, not cut to size). Need to convert an imperial gauge to millimetres? Use our sheet metal gauge-to-mm converter. For I-beams, columns and PFC channels, see the steel beam size chart and RSJ beam calculator.
Frequently asked questions
How do you calculate the weight of a steel plate?
Multiply length × width × thickness (in metres) by the density. Mild steel is 7,850 kg/m³, so a 1m × 1m × 10mm mild steel plate weighs 1 × 1 × 0.01 × 7,850 = 78.5 kg.
What is the density of mild steel?
7,850 kg/m³ (7.85 g/cm³). Galvanised steel is effectively the same — the zinc coating adds a negligible amount for weight purposes.
How much does an 8x4 sheet of steel weigh?
An 8ft × 4ft (2440 × 1220mm) mild steel sheet weighs about 23 kg at 1mm thick, 47 kg at 2mm and 70 kg at 3mm — roughly 23 kg per millimetre of thickness.
What are the densities of stainless steel and aluminium?
Stainless steel 304 is about 7,930 kg/m³ and 316 about 7,980 kg/m³. Aluminium is about 2,710 kg/m³ — roughly a third of steel — so aluminium of the same size weighs about a third as much.
How accurate is the metal weight calculator?
It uses standard published densities, so results are indicative. Actual weight varies slightly with the specific alloy and the rolling tolerance of the material, usually within a few per cent.