The theoretical mass of a circular hollow section (CHS) depends on its outside diameter, nominal wall thickness and steel density. For carbon steel with an assumed density of 7,850 kg/m³, a convenient formula is W = 0.02466 × t × (D − t) kg/m, where D and t are in millimeters. For example, a 168.3 × 6.3 mm CHS has a theoretical mass of approximately 25.17 kg/m, or 151.0 kg for a 6 m length.
CHS Dimensions and Weight
A circular hollow section is a round steel structural member with a hollow cross-section. Structural CHS is generally specified by outside diameter, nominal wall thickness, steel grade and the relevant product standard. Pipe specified by nominal pipe size (NPS) and schedule uses a different designation system. NPS 6, for example, has a nominal outside diameter of 168.3 mm rather than exactly 6 inches.
For cold-formed welded structural hollow sections, EN 10219-1 addresses technical delivery conditions and EN 10219-2 addresses tolerances, dimensions and sectional properties. Other markets may use ASTM A500 or AS/NZS 1163. Compare mass tables only after confirming the same dimensional basis and applicable standard.
CHS Weight Formula
For a circular ring, the nominal steel cross-sectional area is A = π/4 × [D² − (D − 2t)²] = π × t × (D − t), in mm². Converting square millimeters to square meters and multiplying by 7,850 kg/m³ gives W = 0.0246615 × t × (D − t) kg/m. The rounded factor 0.02466 is sufficient for routine estimates.
For D = 168.3 mm and t = 6.3 mm, the inside diameter is 155.7 mm and the nominal cross-sectional area is approximately 3,206 mm². The resulting theoretical mass is approximately 25.17 kg/m. The area depends on geometry; the mass also depends on density. For another material density, use W = A × 10⁻⁶ × density (kg/m).
Theoretical CHS Weight Chart
| Outside diameter × wall (mm) | kg/m | kg per 6 m | lb/ft |
| 60.3 × 3.2 | 4.51 | 27.0 | 3.03 |
| 114.3 × 5.0 | 13.48 | 80.9 | 9.06 |
| 168.3 × 6.3 | 25.17 | 151.0 | 16.91 |
| 219.1 × 8.0 | 41.65 | 249.9 | 27.99 |
| 323.9 × 12.5 | 95.99 | 576.0 | 64.51 |
Values are calculated using nominal dimensions and an assumed density of 7,850 kg/m³. They are not a guaranteed measured mass or an indication that every listed size is available under every structural standard. For other lengths, multiply kg/m by the required length in meters.
Why Actual Weight Differs
Dimensional Tolerances
Manufacturing tolerances permit differences between actual and nominal dimensions. The applicable tolerance depends on the product standard, edition, section size and measurement being assessed. Do not apply one general percentage to every diameter or wall. For procurement and lifting calculations, distinguish the theoretical nominal mass from verified actual mass and consider the applicable contractual tolerances.
Galvanizing and Other Coatings
Hot-dip galvanizing adds zinc to exposed surfaces and therefore increases mass. The increase depends on the actual coated surface area and coating thickness. EN ISO 1461 requirements depend on the product and material thickness; a single coating thickness must not be assumed for every CHS. Paint and other coatings can also affect finished mass. Request coating information when accurate shipped weight is required.
Net and Gross Shipping Weight
Net mass generally refers to the steel product under the agreed measurement basis, while gross shipping mass includes packing materials such as straps, supports, caps and protective wrapping. Packing lists should identify the basis used. For freight planning, use the confirmed shipment mass rather than only a theoretical formula.
How Weight Affects Structural Selection
A larger diameter or thicker wall normally increases steel cross-sectional area and mass per meter. Structural performance, however, cannot be determined from weight alone. Grade, section geometry, buckling, connection design, service conditions and the applicable structural design code must all be considered.
Theoretical mass is useful for initial design comparisons, budgeting and quantity takeoffs. Purchase orders should specify the standard, grade, outside diameter, nominal wall, length, surface finish and agreed weight basis. Where lifting or shipping limits are critical, request a verified packing list and appropriate inspection documentation.
Ordering CHS from LONGMA
LONGMA manufactures ERW and LSAW round steel pipe, with a 230,000 m² production facility and annual output exceeding 500,000 tonnes. For a circular hollow section inquiry, provide outside diameter, nominal wall thickness, grade, product standard, length, quantity and coating requirements. The team can confirm the relevant manufacturing route and quotation details at info@ilongma.com.
FAQ
How do I calculate CHS weight per meter?
For carbon steel at an assumed density of 7,850 kg/m³, use W = 0.02466 × t × (D − t) kg/m, with both D and t in millimeters.
How much does a 6 m CHS weigh?
Multiply the calculated kg/m value by 6. A nominal 168.3 × 6.3 mm CHS weighs approximately 151.0 kg for 6 m before considering dimensional variation, coatings or packaging.
Is the theoretical weight the shipping weight?
No. Actual product dimensions, coatings and packing materials can change shipment mass. Confirm the gross mass from the supplier’s shipping documentation.
Does galvanizing change CHS weight?
Yes. Zinc coating adds mass; the amount depends on the coated area and actual coating thickness.
