How to calculate steel weight
The weight of a steel section depends on its cross-sectional area, its length and the density of the steel. The formula is:
Weight per metre (kg/m) = Cross-sectional area (mm²) × Density (kg/m³) ÷ 1,000,000
Carbon steel has a density of 7,850 kg/m³. The steel weight calculator above applies this automatically for each profile, then multiplies by your length and quantity to give the total weight in kg and tonnes.
Steel weight per metre — quick reference
| Section | Example size | Weight |
|---|---|---|
| Steel plate | 100 × 10 mm | 7.85 kg/m |
| Round bar | Ø20 mm | 2.47 kg/m |
| Square bar | 20 × 20 mm | 3.14 kg/m |
| Equal angle | 65 × 65 × 6 mm | 5.84 kg/m |
| Square tube (SHS) | 80 × 80 × 4 mm | 9.41 kg/m |
Steel densities used
| Material | Density (kg/m³) |
|---|---|
| Carbon / Mild Steel | 7,850 |
| Stainless Steel | 8,000 |
| Aluminium | 2,710 |