What is the difference between square and rectangular tube?

Only the aspect ratio. Square tube has equal sides and behaves the same in both bending directions; rectangular tube is deeper than it is wide, so it is much stiffer in one direction and much weaker in the other. Both are specified the same way in ASTM A500 and share the same wall thickness series.

How do I read a rectangular tube size?

Depth × width × wall thickness, depth first. HSS4×6×1/4 is 4 in deep and 6 in wide with a 1/4 in wall. The order matters because the two orientations have different stiffness — laying the same tube on edge instead of flat can more than double its bending stiffness.

How much does 4x6 rectangular tube weigh?

15.62 lb/ft in a 1/4 in wall, 22.51 lb/ft in 3/8 in and 11.6 lb/ft in 3/16 in. The weight depends only on the perimeter and wall thickness, so it is the same whichever way the tube is oriented — only the stiffness changes with orientation.

Which orientation is stronger?

With the larger dimension vertical. A 4×6 tube set on edge (6 in deep) is about twice as stiff in bending as the same tube laid flat, because the moment of inertia scales with the cube of depth. Set the long dimension in the direction of the bending load.

Can I use rectangular tube as a beam?

Yes, and it is efficient when the load direction is known. It is weaker about its minor axis, so it needs lateral bracing or a load path that does not bend it that way. Where the load direction reverses or is uncertain, square tube avoids the problem at a modest weight penalty.

Rectangular Tube Sizes

Depth, width, wall thickness, area and weight per foot for 21 HSS rectangular tube sizes from 2×3 to 8×12, with metric equivalents.

Data verified 2026-09-29 · based on ASTM A500/A500M-23

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HSS Rectangular Tube Dimensions and Weight (ASTM A500)

Size^[1]	Depth in^[1]	Width in^[1]	Wall in^[1]	Area in²^[3]	Weight lb/ft^[3]	Weight kg/m^[3]	Depth mm^[2]	Width mm^[2]	Wall mm^[2]
HSS2×3×0.125 #	2	3	0.125	1.147	3.90	5.81	50.8	76.2	3.17
HSS2×3×0.188 #	2	3	0.188	1.648	5.61	8.34	50.8	76.2	4.78
HSS2×4×0.125 #	2	4	0.125	1.397	4.76	7.08	50.8	101.6	3.17
HSS2×4×0.188 #	2	4	0.188	2.024	6.89	10.25	50.8	101.6	4.78
HSS3×4×0.188 #	3	4	0.188	2.400	8.17	12.15	76.2	101.6	4.78
HSS3×4×0.25 #	3	4	0.25	3.089	10.51	15.64	76.2	101.6	6.35
HSS3×5×0.188 #	3	5	0.188	2.776	9.45	14.06	76.2	127.0	4.78
HSS3×5×0.25 #	3	5	0.25	3.589	12.21	18.18	76.2	127.0	6.35
HSS4×6×0.188 #	4	6	0.188	3.528	12.01	17.87	101.6	152.4	4.78
HSS4×6×0.25 #	4	6	0.25	4.589	15.62	23.24	101.6	152.4	6.35
HSS4×6×0.375 #	4	6	0.375	6.575	22.38	33.30	101.6	152.4	9.52
HSS4×8×0.25 #	4	8	0.25	5.589	19.02	28.31	101.6	203.2	6.35
HSS4×8×0.375 #	4	8	0.375	8.075	27.48	40.90	101.6	203.2	9.52
HSS5×7×0.25 #	5	7	0.25	5.589	19.02	28.31	127.0	177.8	6.35
HSS6×8×0.25 #	6	8	0.25	6.589	22.42	33.37	152.4	203.2	6.35
HSS6×8×0.375 #	6	8	0.375	9.575	32.59	48.49	152.4	203.2	9.52
HSS6×10×0.25 #	6	10	0.25	7.589	25.83	38.43	152.4	254.0	6.35
HSS6×10×0.375 #	6	10	0.375	11.075	37.69	56.09	152.4	254.0	9.52
HSS8×10×0.375 #	8	10	0.375	12.575	42.80	63.69	203.2	254.0	9.52
HSS8×12×0.375 #	8	12	0.375	14.075	47.90	71.28	203.2	304.8	9.52
HSS8×12×0.5 #	8	12	0.5	18.356	62.47	92.97	203.2	304.8	12.70

The designation gives depth × width × wall, depth first — so HSS4×6×1/4 is 4 in deep and 6 in wide, and it is a different tube from HSS6×4×1/4 in bending even though the weight is identical. Orientation matters: a rectangular tube is substantially stiffer bent about its strong axis, so a 4×6 laid on edge behaves very differently from the same tube laid flat.

Weights are computed from the section geometry with the A500 corner radii and verified against published values on every row. As with square tube, wall thickness and depth are independent choices and together they set both the strength and the weight.

Orientation Is a Design Decision

A rectangular tube has two very different moments of inertia, and which one applies depends on how it is set. A 4×6 tube is roughly twice as stiff bent about its strong axis (6 in depth) as about its weak axis (4 in depth), and the difference grows with the depth ratio.

Rectangular tube exists precisely to exploit that. Where a member is loaded mainly in one plane — a beam, a header, a machine frame rail — a rectangular section puts the material where it is needed and nowhere else, which is more efficient than a square tube of the same weight. The cost is that it is weak about the other axis and must be braced or oriented carefully.

Square tube is the choice when the loading direction is uncertain or reverses, and round tube when torsion is significant. The three shapes are not interchangeable; they are three answers to different loading questions at the same weight.

Frequently Asked Questions

What is the difference between square and rectangular tube?: Only the aspect ratio. Square tube has equal sides and behaves the same in both bending directions; rectangular tube is deeper than it is wide, so it is much stiffer in one direction and much weaker in the other. Both are specified the same way in ASTM A500 and share the same wall thickness series.
How do I read a rectangular tube size?: Depth × width × wall thickness, depth first. HSS4×6×1/4 is 4 in deep and 6 in wide with a 1/4 in wall. The order matters because the two orientations have different stiffness — laying the same tube on edge instead of flat can more than double its bending stiffness.
How much does 4x6 rectangular tube weigh?: 15.62 lb/ft in a 1/4 in wall, 22.51 lb/ft in 3/8 in and 11.6 lb/ft in 3/16 in. The weight depends only on the perimeter and wall thickness, so it is the same whichever way the tube is oriented — only the stiffness changes with orientation.
Which orientation is stronger?: With the larger dimension vertical. A 4×6 tube set on edge (6 in deep) is about twice as stiff in bending as the same tube laid flat, because the moment of inertia scales with the cube of depth. Set the long dimension in the direction of the bending load.
Can I use rectangular tube as a beam?: Yes, and it is efficient when the load direction is known. It is weaker about its minor axis, so it needs lateral bracing or a load path that does not bend it that way. Where the load direction reverses or is uncertain, square tube avoids the problem at a modest weight penalty.

Value Sources

Each data column on this page is tied to the source it came from. The numbers in square brackets correspond to the table headers above.

#	Source	Type	Revision / method
[1]	ASTM A500 — Cold-Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes	standard	ASTM A500/A500M-23
[2]	Section area and weight computed from the section geometry	derived	Computed at build time from the closed-form area formula for the section shape, multiplied by 12 in/ft and the steel density 0.2836 lb/in³. Every row is verified against a published weight held as a known-value check at 1% tolerance, so an error in either the geometry or the formula fails the build.
[3]	Section area and weight computed from the section geometry	derived	Computed at build time from the closed-form area formula for the section shape, multiplied by 12 in/ft and the steel density 0.2836 lb/in³. Every row is verified against a published weight held as a known-value check at 1% tolerance, so an error in either the geometry or the formula fails the build.

Data Sources

Standard	Revision	What it covers on this page
ASTM A500 — Cold-Formed Welded and Seamless Carbon Steel Structural Tubing	ASTM A500/A500M-23	the sizes, walls and corner radii
AISC Steel Construction Manual, Shapes Database	AISC 15th edition (2017)	the published weights used as anchors
ASTM A6/A6M	ASTM A6/A6M-24	the steel density and weight tolerances

Cross-checked against:

Every weight recomputed from the A500 corner-radius area formula at build time
Four rows held as known-value checks against published A500 weights at 1% tolerance
The designation order verified — depth first — so the orientation columns cannot be transposed
Metric conversions recomputed for every row

Derived values — the following values on this page are calculated, not taken directly from the standard:

Value	How it is derived
Area and weight	A = 2t(h + b − 2t) − (4 − π)·3t², using the A500 outside corner radius of 2t. Weight = A × 12 × 0.2836, verified at build time against published weights.
Metric dimensions	Inches × 25.4, recomputed at build time.

Weights are computed from nominal geometry at the standard steel density. Section properties I, S and r are not given and should come from the AISC Shapes Database, since they depend on the corner radii and on the effective width of slender plate elements. Orientation of the tube is a design decision the table cannot make.

Accuracy and use. The values on this page are compiled from the published standards and cross-checked sources listed above. Where values are derived, the derivation is stated. No warranty, express or implied, is made as to the accuracy or completeness of this information, and no liability is accepted for any loss or damage arising from its use. Engineering reference data is provided for guidance in preliminary work — before a value is used for design, fabrication or acceptance testing, verify it against the current revision of the governing standard and against your own inspection. The user assumes all risk and responsibility in connection with the use of this information.

Cite This Page

Every value on this page is traceable to the sources listed above. If you use the data in a document, paper or report, cite it as:

Plain text

Engineering Reference. "Rectangular Tube Sizes." https://refmanual.com/charts/rectangular-tube-sizes/ (accessed 2026-09-29). Data from ASTM A500 — Cold-Formed Welded and Seamless Carbon Steel Structural Tubing, ASTM A500/A500M-23.

BibTeX

@misc{rectangular-tube-sizes,
  title        = {Rectangular Tube Sizes},
  author       = {{Engineering Reference}},
  howpublished = {\url{https://refmanual.com/charts/rectangular-tube-sizes/}},
  note         = {Accessed: 2026-09-29},
  source       = {ASTM A500 — Cold-Formed Welded and Seamless Carbon Steel Structural Tubing, ASTM A500/A500M-23}
}

RIS (EndNote, Zotero, Mendeley)

TY  - ELEC
TI  - Rectangular Tube Sizes
AU  - Engineering Reference
PB  - Engineering Reference
UR  - https://refmanual.com/charts/rectangular-tube-sizes/
PY  - 2026
DA  - 2026-09-29
N1  - Source: ASTM A500 — Cold-Formed Welded and Seamless Carbon Steel Structural Tubing, ASTM A500/A500M-23
ER  -

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