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Carbon steel square tubes are widely used in structural construction, machinery manufacturing, infrastructure, equipment frames, and general fabrication because of their high strength, excellent weldability, and cost-effectiveness. They are available in a wide range of outside dimensions, wall thicknesses, lengths, and material grades to meet different engineering and fabrication requirements.
This guide provides standard carbon steel square tube dimensions in both metric and imperial units, together with wall thicknesses, theoretical weights, dimensional tolerances, and common supply specifications to help engineers, fabricators, and purchasers compare available sizes more efficiently.
Square tube and square hollow section (SHS) are often used interchangeably in international standards. Carbon steel square tubes are specified by outside dimensions (OD × OD) and wall thickness, rather than by Schedule numbers used for round steel pipes. Depending on the applicable standard, dimensions may be expressed in either imperial units (inches) or metric units (millimeters).
Standard product specifications typically include outside dimensions, wall thickness, theoretical weight, production length, and dimensional tolerances.
The following tables summarize the most commonly available carbon steel square tube sizes used in structural, mechanical, and fabrication applications.
Imperial sizes are primarily used in the North American market and are commonly manufactured in accordance with ASTM A500 Grade B and Grade C for structural hollow sections.
| Size Class | Outside Dimensions (in) | Wall Thickness (in) | Nominal Weight (lbs/ft) | Standard Length (ft) |
|---|---|---|---|---|
| Small Sizes | 1" × 1" |
0.065 (16 ga) 0.120 (11 ga) |
0.81 1.36 |
20 / 24 |
| 1-1/2" × 1-1/2" |
0.065 (16 ga) 0.120 (11 ga) 0.188 (3/16") |
1.26 2.17 3.05 |
20 / 24 | |
| 2" × 2" |
0.065 (16 ga) 0.120 (11 ga) 0.188 (3/16") 0.250 (1/4") |
1.70 2.99 4.32 5.41 |
20 / 24 / 40 | |
| Medium Sizes | 3" × 3" |
0.120 (11 ga) 0.188 (3/16") 0.250 (1/4") 0.375 (3/8") |
4.62 6.87 8.81 12.16 |
20 / 24 / 40 |
| 4" × 4" |
0.128 (1/8") 0.188 (3/16") 0.250 (1/4") 0.375 (3/8") 0.500 (1/2") |
6.46 9.42 12.21 17.27 21.63 |
20 / 24 / 40 / 48 | |
| 6" × 6" |
0.188 (3/16") 0.250 (1/4") 0.375 (3/8") 0.500 (1/2") |
14.53 19.02 27.48 35.24 |
20 / 24 / 40 / 48 | |
| Large Sizes | 8" × 8" |
0.250 (1/4") 0.375 (3/8") 0.500 (1/2") |
25.82 37.69 48.85 |
20 to 48 |
| 10" × 10" |
0.250 (1/4") 0.375 (3/8") 0.500 (1/2") |
32.63 47.90 62.46 |
20 to 48 | |
| 12" × 12" |
0.250 (1/4") 0.375 (3/8") 0.500 (1/2") 0.625 (5/8") |
39.43 58.10 76.07 93.34 |
20 to 48 | |
| Jumbo Sizes | 16" × 16" |
0.375 (3/8") 0.500 (1/2") 0.625 (5/8") |
78.52 103.30 127.36 |
Up to 60 |
| 22" × 22" |
0.500 (1/2") 0.750 (3/4") 1.000 (1") |
144.15 211.30 276.00 |
Up to 60 |
Metric square tube sizes are widely used throughout Europe, Asia, Australia, and many international engineering projects. These products are commonly manufactured to EN 10219, EN 10210, GB/T 6728, and AS/NZS 1163 standards.
| Size Class | Outside Dimensions (mm) | Wall Thickness (mm) | Nominal Weight (kg/m) | Standard Length (m) |
|---|---|---|---|---|
| Small Sizes | 20 × 20 |
1.6 2.0 |
0.89 1.07 |
6 |
| 40 × 40 |
1.6 2.0 3.0 |
1.94 2.41 3.47 |
6 / 8 | |
| 50 × 50 |
2.0 3.0 4.0 |
2.93 4.25 5.45 |
6 / 8 | |
| Medium Sizes | 75 × 75 |
3.0 4.0 5.0 6.0 |
6.64 8.62 10.51 12.36 |
6 / 8 / 12 |
| 100 × 100 |
3.0 4.0 5.0 6.0 8.0 |
8.96 11.72 14.41 17.04 22.06 |
6 / 8 / 12 | |
| 150 × 150 |
4.0 5.0 6.0 8.0 10.0 |
18.00 22.26 26.46 34.62 42.33 |
8 / 12 | |
| Large Sizes | 200 × 200 |
5.0 6.0 8.0 10.0 12.5 |
30.11 35.88 47.18 58.03 71.07 |
12 / 15 |
| 300 × 300 |
6.0 8.0 10.0 12.5 16.0 |
54.72 72.30 89.43 110.31 138.96 |
12 / 15 | |
| Jumbo Sizes | 400 × 400 |
10.0 12.5 16.0 20.0 |
121.00 149.00 189.00 233.00 |
12 to 18 |
| 500 × 500 |
12.5 16.0 22.0 25.0 |
189.00 239.00 324.00 365.00 |
12 to 18 |
Manufacturing tolerances ensure dimensional consistency and interchangeability for structural fabrication. The exact allowable deviations depend on the applicable manufacturing standard.
| Item | ASTM A500 | EN 10219 |
|---|---|---|
| Outside Dimensions | ±0.020" to 1% | According to EN tolerance class |
| Wall Thickness | ±10% | Standard tolerance |
| Straightness | 1/8 in per 5 ft | According to EN 10219 |
| Squareness | 90° ±1.5° | Standard requirement |
The permissible dimensional deviation is defined by the applicable manufacturing standard. Actual tolerances should always be verified against the relevant specification before procurement or fabrication.
The following table lists the theoretical weights of commonly used carbon steel square tube sizes. These values are commonly used for preliminary material estimation and quotation.
| Outside Dimensions | Wall Thickness | Theoretical Weight |
|---|---|---|
| 20 × 20 mm | 2.0 mm | 1.07 kg/m |
| 25 × 25 mm | 2.0 mm | 1.39 kg/m |
| 40 × 40 mm | 3.0 mm | 3.47 kg/m |
| 50 × 50 mm | 4.0 mm | 5.45 kg/m |
| 75 × 75 mm | 5.0 mm | 10.51 kg/m |
| 100 × 100 mm | 6.0 mm | 17.04 kg/m |
| 150 × 150 mm | 8.0 mm | 34.62 kg/m |
| 200 × 200 mm | 10.0 mm | 58.03 kg/m |
| 300 × 300 mm | 12.5 mm | 110.31 kg/m |
| 400 × 400 mm | 16.0 mm | 189.00 kg/m |
For additional sizes or custom dimensions, refer to our Carbon Steel Pipe Weight Calculator for detailed weight formulas and calculation methods.
Besides dimensions and wall thickness, purchasers often evaluate carbon steel square tubes based on manufacturing specifications, delivery conditions, inspection requirements, and certification. The following table summarizes the standard product specifications commonly available for structural and mechanical applications.
| Item | Standard Specification |
|---|---|
| Product Type | Welded Square Hollow Section (SHS), Seamless Square Tube (available for selected sizes) |
| Outside Dimensions | 10 × 10 mm to 500 × 500 mm (custom sizes available) |
| Wall Thickness | 0.8 mm to 25 mm |
| Standard Length | 6 m, 9 m, 12 m, or custom cut lengths |
| Material Grades | Q195, Q235, Q355, ASTM A500 Grade B/C, ASTM A36, S235, S355 |
| Manufacturing Standards | ASTM A500, ASTM A513, EN 10219, EN 10210, JIS G3466, GB/T 6728 |
| Surface Finish | Black, Oiled, Pickled, Hot-dip Galvanized, Primer Painted |
| End Finish | Plain Ends, Deburred Ends, Cut to Length |
| Dimensional Tolerance | According to the applicable manufacturing standard |
| Inspection | Visual Inspection, Dimensional Inspection, Mechanical Testing, Chemical Analysis (upon request) |
| Certification | Mill Test Certificate (EN 10204 3.1), Third-party Inspection Available |
| Packaging | Steel Strapping, Bundles, Waterproof Packing, Export Seaworthy Packaging |
Most structural square tubes are supplied with mill test certificates, dimensional inspection, and export packaging, while custom lengths, surface finishes, and special processing can be provided upon request.
| Application | Recommended Size | Typical Wall Thickness |
|---|---|---|
| Furniture | 20×20–30×30 mm | 1.0–2.0 mm |
| Handrails & Fences | 30×30–50×50 mm | 1.5–3.0 mm |
| Machine Frames | 50×50–100×100 mm | 3.0–6.0 mm |
| Structural Columns | 100×100–200×200 mm | 4.0–10.0 mm |
| Heavy Structures & Bridges | ≥200×200 mm | ≥8.0 mm |
The recommended sizes above are for general reference only. Final selection should be based on design loads, applicable standards, and project requirements.
Q1. What are the standard sizes of carbon steel square tubes?
Standard carbon steel square tubes are available in metric sizes from 20 × 20 mm to 500 × 500 mm and imperial sizes from 1 × 1 in. to 22 × 22 in. The available wall thickness depends on the selected size and manufacturing standard.
Q2. What is the standard length of carbon steel square tubing?
Standard production lengths are 6 m, 9 m, and 12 m for metric products and 20 ft, 24 ft, 40 ft, and 48 ft for imperial products. Custom cut lengths are also available from many manufacturers.
Q3. What wall thicknesses are available?
Wall thickness typically ranges from 0.8 mm to 16 mm, depending on the tube size and applicable standard. Larger sections are generally produced with thicker walls for higher structural strength.
Q4. What is the largest standard carbon steel square tube size?
Common manufacturing standards include ASTM A500, ASTM A513, EN 10219, EN 10210, JIS G3466, and GB/T 6728, covering structural, mechanical, and cold-formed square tubing.
Q5. How is the weight of a carbon steel square tube determined?
The theoretical weight of a square tube is based on its outside dimensions and wall thickness. Standard weight tables provide quick estimates, while weight calculators can be used for custom sizes.
Q6. Can carbon steel square tubes be supplied in custom sizes?
Yes. Manufacturers can provide custom lengths, wall thicknesses, end finishes, and surface treatments based on project requirements, although standard sizes usually offer better availability and lower cost.
Carbon steel square tubes are available in a wide range of standard dimensions, wall thicknesses, lengths, and material grades to meet different structural and mechanical requirements. Need a size that is not listed above? Contact us for custom dimensions, lengths, and project-specific manufacturing solutions.
Read more:
- Carbon Steel Pipe Material Grade
- ASTM vs API vs EN Standards for Seamless Carbon Steel Pipes
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