Steel weights
Circular hollow section (tube) weight per metre
- where
- cross-sectional area (mm²)
- wall thickness (mm)
- outside diameter (mm)
- mass per metre (kg/m)
- steel density (kg/m³)
- total mass (kg)
- total length (m)
- outside surface area per metre (m²/m)
Explain this equation
Works out the cross-section, weight and outside surface area of a circular hollow section or tube.
The steel in a tube is a ring. Its area is exactly π times the wall thickness times the mean diameter, D − t. Area times density, divided by a million, gives kg per metre. The outside surface per metre is the circumference πD, converted from millimetres to metres, which is handy for paint quantities.
The ring area π(D² − d²)/4 simplifies to π t (D − t).
Sense check: 168.3 × 6.3 CHS is about 3206 mm², or 25.2 kg/m, matching published tables, with about 0.53 m² of outside surface per metre.
Watch out: use the actual outside diameter (for example 168.3), not the nominal bore size.
Mass per metre of round tube (CHS) from its outside diameter and wall thickness, with the outside surface area for painting.
Enter your values to see the result.
Good to know
The steel area of a tube is π × t × (D − t), which is the same as the difference of the outer and inner circles. Mass uses 7850 kg/m³, the density BS EN 10210-2 and BS EN 10219-2 use for tabulated masses, so the result matches the published tables.
Common mistake
Entering the inside diameter or the nominal bore (as used for pipe) instead of the actual outside diameter. A "6 inch" pipe is 168.3 mm OD.
Limits
Nominal mass. Wall thickness tolerances (up to about ±10% for hollow sections) affect actual weight.
Sources
- BS EN 10210-2:2019 Hot finished steel structural hollow sections – Part 2: Tolerances, dimensions and sectional properties (density 7.85 kg/dm³)
- BS EN 10219-2:2019 Cold formed welded steel structural hollow sections – Part 2: Tolerances, dimensions and sectional properties (mass from density 7.85 kg/dm³; corner radius rules and area formula)
- SCI / Steel for Life Blue Book: Steel building design – design data (section property formulas and tables for UKB, UKC, hot-finished and cold-formed hollow sections)
Results are calculations from the published methods and figures shown, and depend on the data you enter. Follow the welding procedure specification (WPS), BS EN ISO 15614/9606, BS EN 1090, BS EN 1993 and manufacturers’ data. Structural welds need qualified welders and engineered designs.