A fabricator quoting for a shed in Pune's Bhosari or a staircase in Chennai's Ambattur will ask the same question: square or rectangular tube? RHS vs SHS is not just a matter of looks. A rectangular hollow section placed the right way up carries more load for the same steel in one direction, while a square section is equally strong both ways. This guide explains the difference in practical terms.
The names
- SHS: square hollow section, equal sides (40 × 40 × 2).
- RHS: rectangular hollow section, two different sides (60 × 40 × 2.6).
- CHS: circular hollow section, round pipe.
Sizes are written as outside dimensions × wall thickness, in millimetres.
Why orientation matters for RHS
A beam resists bending mainly through the material farthest from its centre. An RHS with its longer side vertical puts more steel top and bottom, so it is much stiffer in that direction. Turned on its side, the same tube is much weaker. That is why purlins and beams are always placed “standing”, long side vertical.
Is RHS stronger than SHS?
In one direction, yes, for the same weight. In the other direction it is weaker. SHS is equally strong both ways, which suits columns and posts that can be loaded from any side.
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Typical uses
| Section | Typical uses | Why |
|---|---|---|
| RHS | Purlins, beams, door and window frames, staircase stringers, shutter frames | Loads come mainly from one direction |
| SHS | Columns, posts, gate frames, railings, furniture legs | Loads from any direction; neat look |
| CHS | Handrails, scaffolding, fluid lines | Good in twisting; comfortable to grip |
Weight comparison
RHS area = 2t(A + B) − 4t² SHS area = 4t(A − t) kg/m (mild steel) = area × 0.00785
A 60 × 40 × 2.6 RHS weighs about 3.87 kg/m; a 50 × 50 × 2.6 SHS, with the same perimeter, weighs about the same, 3.87 kg/m. With equal steel, the RHS placed upright is stiffer for a beam, while the SHS is the better post.
Practical points
- Ask the engineer for structural members; spans, loads and connections decide the size.
- Mark the orientation on fabrication drawings so beams aren't installed flat.
- Check weights on delivery; a large shortfall usually means a thinner wall.
- Prime inside and out where possible; hollow sections rust from the inside if water enters.
The rectangular tube weight calculator gives kg per metre and per piece for any RHS size in MS, stainless steel or aluminium; the square tube calculator does the same for SHS.
Frequently asked questions
What is the difference between RHS and SHS?
RHS is a rectangular hollow section with two different sides; SHS is square with equal sides.
Which is stronger, RHS or SHS?
RHS placed with the long side vertical is stiffer as a beam for the same weight; SHS is equally strong in both directions.
Which way should a rectangular tube purlin face?
With the longer side vertical.
How is RHS weight calculated?
Area = 2t(A + B) − 4t² in mm²; for mild steel, kg/m = area × 0.00785.
Where is SHS used?
Columns, posts, gate frames, railings and furniture.
Keep reading
- Rectangular Tube Weight Calculator: the free tool this guide explains.
- All construction calculators
- Square Tube Size for Gate, Grill and Shed: A Buyer's Guide
Sources: IS 4923 (hollow steel sections); basic beam theory (section modulus about each axis).