Hollow Section Weight Calculator UK

Understanding Hollow Section Weight Calculations

Hollow structural sections including square SHS, rectangular RHS, and circular CHS tubes form essential components in modern steel construction, with accurate weight calculation critical for structural design, material procurement, and cost estimation. Weight calculations consider section dimensions, wall thickness, length, and steel density typically 7,850 kilograms per cubic metre for standard carbon steel conforming to BS EN 10210 specifications. Understanding weight relationships enables material quantity assessment for projects ranging from lightweight architectural frameworks to heavy industrial structures, ensuring adequate specification while avoiding over-engineering adding unnecessary cost and weight to structural systems.

Hollow sections offer superior strength-to-weight ratios compared to solid sections, with efficient material distribution around section perimeters providing excellent bending and torsional resistance. This structural efficiency reduces material consumption and overall project weight, benefiting foundation design, transportation logistics, and erection sequencing. Standard UK sections follow metric sizing with designations indicating nominal dimensions and wall thickness—for example, SHS 100×100×5 represents 100mm square section with 5mm wall thickness. Manufacturers produce sections to tight dimensional tolerances ensuring predictable weights and structural properties for design calculations and material ordering.

Square Hollow Section SHS Weight

Square hollow sections calculate weight using the formula multiplying perimeter by wall thickness, length, and material density. For SHS with side dimension a and thickness t, the weight per metre approximates 4(a-t)×t×0.00785 kilograms, where 0.00785 represents steel density conversion factor. A common SHS 100×100×5 section weighs approximately 14.2 kg per metre, making 6-metre standard length weigh 85 kilograms requiring appropriate handling equipment and lifting capacity for safe installation on construction sites.

Standard SHS sizes range from 40×40mm for light architectural applications to 400×400mm for major structural columns and compression members. Wall thickness varies from 2.5mm for lightweight sections to 16mm for heavy-duty applications requiring enhanced load capacity. The uniform dimensions of square sections provide equal strength in both axes, simplifying connection details and design calculations compared to asymmetric alternatives. Material efficiency improves with larger sections and optimized thickness selections matching structural requirements without excessive material consumption.

Rectangular Hollow Section RHS Weight

Rectangular hollow sections use similar weight calculations accounting for different width and height dimensions. Weight per metre equals 2(a+b-2t)×t×0.00785 where a represents width and b indicates height. Popular RHS 150×100×6 sections weigh approximately 20.9 kg per metre, with asymmetric dimensions providing directional strength variations suitable for beams, purlins, and members experiencing predominant bending in one plane. This optimization reduces material consumption compared to square sections offering equivalent capacity in critical load directions.

RHS sizing spans from 50×25mm minimum sections for handrails and balustrades to 500×300mm maximum sizes for major beams and structural members. The dimensional flexibility enables precise strength matching to loading requirements, with engineers selecting appropriate width-to-height ratios optimizing bending capacity, deflection control, and material economy. Connections require consideration of dimensional asymmetry, with proper orientation ensuring welds and fasteners align with section walls rather than void spaces compromising joint integrity.

Circular Hollow Section CHS Weight

Circular hollow sections calculate weight from outside diameter D and wall thickness t using the formula π(D-t)×t×0.00785 kilograms per metre. Standard CHS 114.3×5 pipe sections commonly used for columns and bracing weigh approximately 13.5 kg per metre. The circular geometry provides uniform strength in all directions, excellent torsional resistance, and aerodynamic profiles reducing wind loading on exposed structures. These characteristics suit applications including flagpoles, transmission towers, offshore platforms, and architectural features requiring omnidirectional capacity and aesthetic appeal.

CHS sizing follows pipe schedule conventions with common diameters including 48.3mm, 60.3mm, 88.9mm, 114.3mm, 168.3mm, and larger sizes to 508mm for major structural applications. Wall thickness increases with diameter maintaining adequate strength and preventing local buckling under compression loading. The smooth external surface simplifies coating application for corrosion protection, while internal accessibility for inspection and maintenance proves more restricted than open sections requiring consideration during design and specification phases.

Standard Section Weights

Manufacturers publish standard weight tables listing common sections with certified weights per metre derived from production specifications and quality control testing. These tabulated values provide convenient reference avoiding manual calculations for routine material ordering and structural documentation. For example, popular structural sections include SHS 100×100×5 at 14.2 kg/m, RHS 150×100×6 at 20.9 kg/m, and CHS 114.3×5 at 13.5 kg/m. Design software databases incorporate standard weights enabling automated quantity takeoffs from structural models generating accurate material schedules and cost estimates.

Actual weights may vary slightly from theoretical calculations due to manufacturing tolerances, material density variations, and production methods. BS EN 10210 specifications define permissible weight tolerances typically ±6% for individual sections and ±4% for batch averages, ensuring reasonable consistency while accommodating inevitable manufacturing variations. Critical applications requiring precise weight control specify tighter tolerances or weigh-measurement verification confirming actual delivered weights matching design assumptions and procurement specifications.

Material Density and Grades

Standard carbon steel density of 7,850 kg/m³ applies to most structural hollow sections manufactured from grades including S275 and S355 conforming to BS EN 10210. Higher-strength steels including S420 and S460 utilize similar densities despite enhanced mechanical properties achieved through alloy additions and heat treatment rather than density changes. Stainless steel hollow sections using austenitic grades demonstrate slightly higher density around 8,000 kg/m³, increasing section weights approximately 2% compared to carbon steel equivalents requiring adjustment in weight calculations and cost estimates.

Grade selection balances strength requirements against cost considerations, with S275 providing economical solutions for lightly loaded applications and S355 offering enhanced capacity for demanding structural roles. The yield strength difference enables smaller S355 sections replacing larger S275 alternatives, potentially reducing weight despite identical density. This optimization improves structural efficiency though premium S355 material costs partially offset weight savings. Comprehensive design evaluation considers material grades, section sizes, and total project costs determining optimal specification balancing performance and economy.

Weight Impact on Costs

Steel pricing typically quotes per tonne, making weight calculations essential for cost estimation. In 2026, structural steel costs £1,100-1,400 per tonne depending on grade, specification, quantity, and market conditions. Standard S275 hollow sections average £1,150-1,250 per tonne, while S355 grades reach £1,250-1,350 per tonne. A project requiring 5 tonnes of RHS 150×100×6 costs approximately £6,000-6,750 for materials before fabrication, surface treatment, delivery, and installation expenses. Accurate weight estimation ensures proper budget allocation and prevents cost overruns from material quantity miscalculations.

Transportation and handling costs correlate directly with weight, affecting delivery charges, crane requirements, and manual handling equipment. Heavy sections requiring mechanical lifting add equipment hire costs while lightweight sections enable manual handling reducing project expenses. Weight optimization through efficient section selection minimizes material costs, transportation expenses, and foundation loads reducing overall project budgets. However, excessive weight reduction compromising structural adequacy proves counterproductive, necessitating balanced design achieving economy without sacrificing safety or performance.

Applications and Selection

Square hollow sections suit column applications providing uniform compression capacity and simple connection detailing. The equal dimensions simplify bolted and welded joints, while torsional rigidity resists twisting under eccentric loading. Typical applications include building columns, space frame nodes, and compression struts in truss systems. Rectangular sections optimize beam applications with depth providing bending resistance and width ensuring lateral stability. Common uses include roof purlins, floor beams, and portal frame rafters where directional loading justifies asymmetric sections.

Circular hollow sections excel in bracing applications where load reversals and omnidirectional forces require uniform capacity. The streamlined profile reduces wind and water loading on exposed structures including offshore platforms, transmission towers, and coastal installations. Aesthetic considerations favor circular sections for architectural exposed steelwork, handrails, and feature columns where visual appearance influences selection. Proper application matching optimizes structural performance and economy, with section type selection considering load characteristics, connection requirements, and project-specific constraints beyond simple strength calculations.

Procurement and Availability

Standard sections maintain good availability from UK steel stockholders and service centers stocking common sizes in 6 or 12-metre lengths. Custom lengths or non-standard dimensions require mill orders with extended lead times of 8-16 weeks and minimum quantity requirements often exceeding 5-10 tonnes. Planning long-lead procurements early in project schedules prevents critical path delays while specifying standard available sections where possible improves delivery reliability and cost control through competitive commodity pricing rather than specialty production premiums.

Section selection considering standard availability balances optimized design against procurement practicality. Slightly oversized standard sections readily available may prove more economical than perfectly optimized custom sections requiring extended procurement and premium pricing. Supplier engagement during design development identifies availability constraints enabling specification adjustments maintaining project schedules and budgets. Large projects justify custom production optimizing material efficiency, while smaller works benefit from standard section selection simplifying procurement and reducing costs through readily available commodity materials.

Standard Hollow Section Weights

SHS Size	Thickness	Weight kg/m	Typical Use
50×50mm	3.0mm	4.38	Light frames, handrails
80×80mm	4.0mm	9.42	Medium columns, bracing
100×100mm	5.0mm	14.2	Standard columns, posts
150×150mm	6.0mm	26.3	Structural columns
200×200mm	8.0mm	48.4	Heavy columns, major supports

RHS Size	Thickness	Weight kg/m	Typical Use
100×50mm	4.0mm	9.13	Light beams, purlins
150×100mm	5.0mm	17.8	Standard beams, lintels
150×100mm	6.0mm	20.9	Medium beams, rafters
200×100mm	6.0mm	26.3	Floor beams, portal frames
250×150mm	8.0mm	47.2	Main beams, heavy loads

Essential Hollow Section Weight Facts

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