Steel weight calculator

How the weight is worked out

Weight = cross-section area × length × density. The calculator finds the area of the shape you choose, multiplies it by the length and by the density of the material, and gives the weight per metre, per piece and for the whole quantity.

• Round bar: area = π ÷ 4 × diameter²
• Hexagon bar: area = 0.866 × across-flats²
• Flat, plate and sheet: area = width × thickness
• Pipe: area = π ÷ 4 × (outside diameter² − inside diameter²)

Quick formulas for mild steel

• Round bar: kg per metre = D² × 0.00617 (D in mm)
• Square bar: kg per metre = A² × 0.00785 (A = side in mm)
• Plate: kg per square metre = thickness (mm) × 7.85

Questions

How do you calculate the weight of an MS round bar?

Weight in kg per metre = diameter² (mm) × 0.00617. For example, a 50 mm bar weighs 50 × 50 × 0.00617 = 15.4 kg per metre. The same thing is often written as D² ÷ 162.

How do you calculate the weight of an MS plate?

Weight in kg = length (m) × width (m) × thickness (mm) × 7.85. A 1 m × 1 m plate 10 mm thick weighs about 78.5 kg.

What is the density of mild steel?

About 7.85 g/cm³, which is 7,850 kg per cubic metre. Stainless steel is slightly heavier (about 7.9–8.0), aluminium about 2.7.

Why does my supplier's weight differ slightly?

Bars and plates are made to size tolerances, and alloys vary a little in density, so actual weights can differ by a few per cent. Suppliers often use their own section-weight tables.