SHS and RHS Hollow Section Weight Calculator — IS 4923

The hollow section weight calculator for SHS and RHS sections uses the outer dimensions and wall thickness to give weight per metre: for square hollow sections, W = 4 × (A − t) × t × 0.00785 kg/m; for rectangular sections, W = 2 × [(A − t) + (B − t)] × t × 0.00785 kg/m — both governed by IS 4923: 1997, the BIS standard used by APL Apollo and Tata Structura.

What IS 4923 Specifies — and Why It Matters for Weight

IS 4923: 1997 is the BIS standard for cold-formed and hot-formed hollow steel sections (HSS) used in structural applications — columns, beams, trusses, gates, railings and fabricated frames. Unlike IS 808 angle or channel sections which are open sections, hollow sections are closed, which gives them superior torsional stiffness and a cleaner aesthetic for architectural and structural work.

The standard defines three yield strength grades. YST 210 (minimum yield 210 MPa) is the most commonly available grade, used for light structural and fabrication work. YST 240 (240 MPa) and YST 310 (310 MPa) are specified for higher-load structural applications. APL Apollo produces all three grades under their branded range; Tata Structura primarily supplies YST 240 and YST 310 for their structural series.

A critical point for weight calculation: the weight per metre is the same across all three yield grades for any given section size. Grade affects mechanical properties — not density or geometry. A 50×50×3 SHS in YST 210 weighs exactly the same per metre as the same section in YST 310. Always confirm the grade separately from the weight calculation.

Hollow section ka weight nikalna IS 4923 ke bina mushkil hota hai — standard ke bina manufacturer ka claimed weight verify karna possible nahi hota.

Square Hollow Section (SHS) Weight Formula

A square hollow section has four walls, each of width (A − t) where A is the outer dimension and t is the wall thickness. The cross-sectional area of steel is:

Area (mm²) = 4 × (A − t) × t

Multiplying by density and converting units:

W (kg/m) = 4 × (A − t) × t × 0.00785

Verification with IS 4923: For a 50×50×3 SHS:

W = 4 × (50 − 3) × 3 × 0.00785 = 4 × 47 × 3 × 0.00785 = 4.43 kg/m

IS 4923 table value for this section: 4.46 kg/m. The 0.03 kg/m difference (0.7%) arises from the corner radius geometry — actual sections have rounded external corners that add a small amount of material not captured by the simplified flat-wall formula. For procurement estimates, the formula is accurate enough. For structural design, always use the IS 4923 tabulated section properties.

Rectangular Hollow Section (RHS) Weight Formula

An RHS has two pairs of parallel walls of different widths. The cross-sectional area is:

Area (mm²) = 2 × [(A − t) + (B − t)] × t

where A is the larger outer dimension and B is the smaller outer dimension. Weight per metre:

W (kg/m) = 2 × [(A − t) + (B − t)] × t × 0.00785

Verification for 100×50×3.2 RHS:

W = 2 × [(100 − 3.2) + (50 − 3.2)] × 3.2 × 0.00785

= 2 × [96.8 + 46.8] × 3.2 × 0.00785

= 2 × 143.6 × 3.2 × 0.00785 = 7.21 kg/m

IS 4923 tabulated value: 7.25 kg/m — again within 0.6%, with the small difference attributable to corner radius geometry.

IS 4923 SHS Weight Table — Square Hollow Sections

Source: IS 4923: 1997 tabulated values. WT = wall thickness. Dash (—) indicates size/thickness not specified in IS 4923 for that combination. Weights in kg/m.

IS 4923 RHS Weight Table — Rectangular Hollow Sections

Source: IS 4923: 1997. Weights in kg/m. Dash (—) = combination not in IS 4923 standard range.

Worked Example — Structural Gate Frame Weight Calculation

A fabrication shop needs to estimate the steel weight for a sliding gate frame: four vertical uprights of 75×75×4 SHS at 2500mm each, and two horizontal top rails of 100×50×3.2 RHS at 3000mm each.

Step 1 — SHS uprights (75×75×4):

From the IS 4923 SHS table: 75×75 at 4.0mm wall = 8.60 kg/m.

Weight per upright = 8.60 × 2.5m = 21.50 kg

Four uprights = 21.50 × 4 = 86.0 kg

Step 2 — RHS top rails (100×50×3.2):

From the IS 4923 RHS table: 100×50 at 3.2mm wall = 6.81 kg/m.

Weight per rail = 6.81 × 3.0m = 20.43 kg

Two rails = 20.43 × 2 = 40.86 kg

Step 3 — Total structural steel:

86.0 + 40.86 = 126.86 kg ≈ 127 kg

Add 10–15% for weld plates, gussets, and infill members, and your total BOM weight for this gate comes to approximately 140–146 kg. At a steel cost of ₹68–72 per kg for APL Apollo hollow sections (market rate, May 2026), this is a material cost of roughly ₹9,500–10,500 before fabrication and finishing.

Cross-check the individual section weights instantly using the Metal Weight Calculator → — select Mild Steel, Hollow Section (Square or Rectangle), enter the dimensions and length.

When planning cuts for multiple gate frames, use the Cut List Optimizer → to determine how many 6m sticks of each section to order, and get the cutting plan that minimises waste.

APL Apollo and Tata Structura — What the Product Catalogues Show

APL Apollo Tubes is the dominant hollow section brand in India, and their weight-per-metre catalogue values are the de facto reference for most fabricators. Comparing APL Apollo's published values against IS 4923 for common sizes — 50×50×3, 75×75×4, 100×50×3.2 — the values match within ±0.05 kg/m. This confirms that IS 4923 tabulated weights are directly applicable to APL Apollo-branded material without any brand-specific correction.

Tata Structura hollow sections are produced under the same IS 4923 specification, primarily in YST 240 and YST 310 grades. Their catalogue also matches the IS 4923 weight table. Where Tata Structura differs is in their surface finish and dimensional consistency — their tolerance on wall thickness is claimed to be tighter than the IS 4923 ±10% nominal, though this is a quality assurance claim rather than a different standard specification.

One thing to watch for with hollow sections: IS 4923 specifies two methods of manufacture — cold forming from HR coil (the most common for sizes up to 100mm) and hot forming for larger sections. The weight per metre is the same calculation regardless of forming method. However, cold-formed sections have square corners with a defined external corner radius; hot-formed sections may have slightly more rounded corners. For the weight calculation, both use the same formula with the nominal dimensions.

Also refer to our MS Angle Weight Per Metre guide → if you're combining angle and hollow sections in the same frame — the procurement estimate logic is identical.