Hollow Section Weight Calculator (RHS / SHS / CHS)

Hollow Section Weight Calculation — RHS, SHS & CHS

Hollow sections come in three standard shapes — RHS (Rectangular Hollow Section), SHS (Square Hollow Section), and CHS (Circular Hollow Section). The weight formula subtracts the inner void volume from the outer volume.

RHS / SHS Formula

For rectangular and square tubes: Weight = [W × H − (W−2t)(H−2t)] × Length × Density. This calculates the cross-sectional area of the metal only (excluding the hollow center), then multiplies by length and density.

Real cold-formed tubes have rounded corners (outer radius about 2× wall thickness for walls up to 6mm, per the EN 10219-2 convention), which removes a little material. This calculator subtracts that corner allowance by default: k × (4 − π) × t² with k = 3 for t ≤ 6mm. The sharp-corner result is typically 2–4% higher — tick "Sharp corners" if your textbook or tender uses that formula.

CHS Formula

For circular hollow sections (round pipes): Weight = π/4 × (OD² − ID²) × Length × Density. This is mathematically identical to the standard pipe weight formula.

RHS (Rectangular Hollow Section) Weight Chart — Mild Steel

Rectangular hollow sections are the most versatile structural tubes in the Indian market. They are used for gate frames, door frames, trusses, and general fabrication. Below are the most commonly available RHS sizes with their weight per meter and per 6-meter length.

SHS (Square Hollow Section) Weight Chart — Mild Steel

Square hollow sections provide equal strength in both axes, making them ideal for columns, posts, and frames where load can come from any direction. They are commonly referred to as "square pipes" or "box pipes" in the Indian market.

RHS and SHS values above are calculated for MS with rounded corners (outer radius ≈ 2t). Manufacturer catalogues (APL Apollo, Tata Structura, Jindal) may differ by 1–3% because of their actual corner radius — use the mill chart for billing.

RHS vs SHS vs CHS — Which Hollow Section to Use?

Choosing the right type of hollow section depends on the structural requirement, aesthetic preference, and the direction of load application. Here is a practical comparison:

For most gate and grill fabrication in India, RHS (60×40, 80×40) is the standard choice. For columns and vertical posts, SHS (50×50, 75×75) is preferred. CHS is used when a tubular aesthetic is desired (handrails, furniture, scaffolding) or for fluid-carrying applications.

IS 4923 — Indian Standard for Hollow Steel Sections

In India, hollow steel sections for structural use are covered under IS 4923 (Hollow Steel Sections for Structural Use — Specification). This standard specifies the dimensions, tolerances, mechanical properties, and testing requirements for square and rectangular hollow sections. Circular hollow sections for structural use are covered separately under IS 1161.

Cold-formed sections are made by bending flat steel strip into shape and welding the seam (ERW process). They are available in thinner walls (1.6mm–6mm) and are more economical for light to medium structural use. Cold-formed sections have rounded corners — the outer corner radius is typically around 2× the wall thickness for thin walls. This is by far the most common type in the Indian market.

Hot-finished sections are formed (or re-formed) at high temperature. They have tighter corners, more uniform properties and are used mainly for heavier walls and demanding structural work. In India they are less common than cold-formed tubes and are often imported or supplied on order — check availability before specifying.

The weight values in this calculator are based on nominal dimensions. Actual weight can differ by a few percent because of thickness tolerance, actual corner radius and the weld bead — check the mill certificate or weighbridge for billing.