Steel Weight Calculator

Steel weight is calculated using the formula: Weight = Volume × Density. First, calculate the cross-sectional area of the shape (e.g. π × r² for round bar), multiply by the length to get volume in mm³, then multiply by the material density. For mild steel the density is 7,850 kg/m³. Our calculator handles all common shapes automatically.

The density of mild steel (carbon steel) is 7,850 kg/m³ or 0.284 lb/in³. This is the standard value used for structural steel, plate, bar, tube, and section weight calculations. Stainless steel is slightly denser at around 8,000 kg/m³, while aluminium is much lighter at 2,710 kg/m³.

A 1-metre length of 50mm diameter mild steel round bar weighs approximately 15.41 kg. Calculation: π × (25mm)² × 1000mm = 1,963,495 mm³ volume, then × 7,850 kg/m³ ÷ 1,000,000,000 = 15.41 kg.

Multiply Width × Length × Thickness × Density. For example, a 1000mm × 2000mm × 10mm mild steel plate: 1.0 × 2.0 × 0.01 × 7,850 = 157 kg. As a rule of thumb, mild steel plate weighs 7.85 kg per square metre per mm of thickness.

RHS (Rectangular Hollow Section) has different width and height dimensions, while SHS (Square Hollow Section) has equal width and height. Both are hollow steel tubes commonly used in structural and fabrication work. Use "Square Tube" in the calculator for SHS and "Rectangular Tube" for RHS.

Mild steel plate weighs 7.85 kg per square metre per mm of thickness. Common examples: 3mm = 23.55 kg/m², 5mm = 39.25 kg/m², 6mm = 47.1 kg/m², 10mm = 78.5 kg/m², 12mm = 94.2 kg/m², 20mm = 157 kg/m².

Corten steel (also called weathering steel) forms a stable, rust-like patina when exposed to the weather, removing the need for painting. It has the same density as mild steel at 7,850 kg/m³, so weight calculations are identical. Common grades include S355J2WP and S355J0WP.

Multiply kilograms by 2.20462 to get pounds. For example, 100 kg = 220.46 lbs. Use the Metric/Imperial toggle at the top of this calculator to switch between mm/kg and inches/lbs automatically.