Square Bar Weight Calculator

Square Bar Weight per Meter Chart (Mild Steel)

A square bar (also called MS square or chowkor sariya) has a simple square cross-section. The weight formula is straightforward: Side × Side × Length × Density. For mild steel, a quick shortcut is Side² × 0.00785 = kg/m (where side is in mm).

Square Bar vs Round Bar Weight

A square bar is always heavier than a round bar of the same nominal dimension. Specifically, a square bar weighs approximately 27.3% more than a round bar of the same dimension, because a circle inscribed inside a square covers only π/4 ≈ 78.5% of the area. For example, a 25mm square bar weighs 4.91 kg/m while a 25mm round bar weighs 3.85 kg/m.

Where Does the 0.00785 Shortcut Come From?

The 0.00785 multiplier is the most commonly used shortcut for calculating MS square bar weight per meter. Here is how it is derived from the full formula:

W = Side² × 1m × ρ = (S/1000)² × 1 × 7850 = S² × 7850 / 1000000 = S² × 0.00785

So when you multiply the side dimension (in mm) squared by 0.00785, you get the weight per meter in kg. This works because the density of mild steel is 7850 kg/m³, and dividing by 1,000,000 converts mm² to m².

For other materials, the multiplier changes: SS 304 uses 0.00793, Aluminium 6061 uses 0.00270, Copper uses 0.00894, and Brass uses 0.00850. However, the calculator above handles all materials automatically — just select from the dropdown.

Comparison with round bar shortcut: For round bars, the equivalent shortcut is D²/162 (or D² × 0.00617). Notice that 0.00785 / 0.00617 = 1.272, which confirms the 27.3% weight difference between square and round bars of the same dimension.

Square Bar vs Square Tube (SHS) — When to Use Which?

Square bars are solid cross-sections with no hollow center. They are used in applications where strength, weight, and machinability matter — machine keys, tool shanks, gate grills, window guards, axles, and decorative ironwork. Because they are solid, they are significantly heavier than hollow tubes of the same outer dimension.

Square tubes (SHS — Square Hollow Sections) are hollow with a defined wall thickness. They are the standard choice for structural frames, columns, trusses, furniture, and gates where strength-to-weight ratio is important. A 50×50mm square tube with 3mm wall weighs about 4.25 kg/m (rounded corners; 4.43 kg/m by the sharp-corner formula), while a 50mm solid square bar weighs 19.63 kg/m — the solid bar is roughly 4.5 times heavier.

Rule of thumb: If the application involves load-bearing structure (frames, columns, trusses), use a square tube. If the application involves machining, grinding, or needs a solid mass (keys, pins, weights, anvils), use a solid square bar. For decorative grills and gates, small solid square bars (10–16mm) are common because they are easy to bend and weld.

Common Square Bar Sizes and Applications in India

Standard supply length for MS square bars in India is 5.5 to 6 meters. Sizes up to 25mm are readily available at local steel shops. Larger sizes (32mm and above) may need to be ordered from stockyards or rolling mills. Bright (cold-drawn) square bars are available in sizes up to 50mm for precision machining applications.

Square Bar Weight Across Different Materials

The weight of a square bar changes proportionally with the material's density. Here is a comparison for a 25mm × 1-meter square bar across commonly used engineering materials:

The multiplier column shows the value to use in the shortcut formula: Side² × Multiplier = kg/m. For MS, the well-known 0.00785 multiplier is simply the density (7850) divided by 1,000,000.