Rectangular steel tubing is a hollow steel section with a rectangular cross-section, sold under many specifications for structural, mechanical and architectural uses. This page narrows to rectangular hollow structural sections (HSS) used in U.S. structural construction, because that is where published dimensions and section properties are standardized. For other shapes, see the square steel tube sizes and the HSS size chart.

AISC defines HSS as manufactured hollow structural sections, typically round, square or rectangular. In the U.S., structural HSS commonly conforms to ASTM A500 or ASTM A1085. Mechanical rectangular tubing may instead be made under standards such as ASTM A513 and can differ in tolerances, materials, wall thicknesses, corner geometry and intended application.

AISC writes a rectangular HSS as HSS depth × width × nominal wall thickness. For example, HSS6×4×1/4 has a nominal 6 in. outside depth, 4 in. outside width and 1/4 in. nominal wall.

Depth is conventionally the larger dimension, and the section is stronger when loaded across that depth. See the strong-axis section for what changes when you turn the tube.

The depth and width in an HSS designation are overall outside dimensions. The inside opening is smaller by the wall thickness on each side, and it has rounded corners, so it is not a perfect rectangle. A 4×2×1/4 tube does not have a 4 in. by 2 in. opening.

ASTM A500 permits a wall-thickness tolerance of about 10 percent, so AISC 360 requires calculations involving thickness to use 0.93 times the nominal wall. This is a design treatment, not a statement that the tube wall is physically 93 percent as thick.

ASTM A500/A500M covers cold-formed welded and seamless carbon steel structural tubing in rounds and shapes for welded, riveted or bolted construction of bridges and buildings and for general structural purposes. A500 covers tubes up to a maximum perimeter of 88 in. and a maximum nominal wall of 1 in. STI notes that domestic producers supply rectangular HSS up to 34 in.

Grade C and Material Strength

Grade C is the predominant A500 grade, with a minimum yield strength of 50 ksi and a tensile strength of 62 ksi for all HSS shapes. Most domestic HSS is dual-graded B and C, and STI recommends specifying Grade C. Material strength is not member capacity: do not convert 50 ksi directly into a load rating.

The 0.93 Design Wall

Because of the allowed wall thickness tolerance of about 10 percent, AISC 360 requires the 0.93 factor on nominal wall in design. That is why A500 design properties in the chart use the design wall column.

ASTM A1085 covers cold-formed welded carbon steel HSS. It adds testing requirements, tighter tolerances and property ranges. The minimum wall tolerance is only -5 percent of nominal and the minimum mass tolerance is -3.5 percent, so AISC allows section properties to use the full nominal wall. A1085 requires a minimum yield strength of 50 ksi (maximum 70 ksi) and a Charpy V-notch test of 25 ft-lb at 40°F.

The A1085 area equals the nominal-wall area, which is why an A1085 HSS6×4×1/4 shows 4.59 in² while an A500 HSS6×4×1/4 shows 4.30 in². Do not mix the two tables unless a specification column identifies each row.

Do not use A500 properties for an unidentified mechanical tube. Pipe schedules do not apply to rectangular HSS; for round pipe terminology see the steel pipe size chart.

These nine families (2×1, 3×2, 4×2, 4×3, 5×3, 6×2, 6×3, 6×4 and 8×4) cover the most searched sizes. Larger rectangular HSS goes up to 34 in. from domestic producers, but a size appearing in a table does not mean every wall is available for it. The full numbers for each family are in the size chart above, so there are no separate pages per size.

Weights depend on the outside perimeter and the nominal wall, which is why HSS6×2 and HSS5×3 weigh the same at the same wall. These are published values, not calculated from idealized sharp-corner geometry. For project totals, use the steel weight calculator or the metal weight calculator, and see the structural steel weight chart for other steel shapes.

Total Weight for Any Length

The area in the chart for an HSS4×2×1/4 is smaller (2.44 in² using the A500 design wall) because the real section has rounded corners and AISC uses the design wall. Published AISC/STI values account for actual HSS geometry.

ASTM A500 rectangular HSS is not a sharp-corner box. STI reports that the maximum corner radius for rectangular and square A500 HSS is 3t. Different effective radii are used for different calculations: STI describes 1.5t in slenderness calculations and 2.25t for the workable flat. Do not calculate published HSS properties as though the section were four sharp-corner plates.

Rectangular HSS for Beams and Columns

Properties that matter, and what this page does not decide.

Beams

For bending members the relevant properties are Ix, Sx and the plastic modulus Zx, along with orientation. Do not choose a beam size from span alone; use the steel beam size chart for other shapes and the beam load calculator or beam deflection calculator for load and deflection checks.

Columns

For compression members the relevant properties are area, rx, ry, effective length and slenderness, with buckling governed by AISC 360. STI’s HSS selection tools perform compression checks to AISC 360 rather than relying on size alone.

Connections

An HSS is a closed section, so connections face access limits, wall-thickness limits, local yielding and effective weld length. STI publishes dedicated HSS connection resources; connection design is outside this chart. See also structural steel shapes for open-section alternatives.

How Much Weight Can Rectangular Steel Tube Hold?

There is no universal answer, and this page does not give one.

⚠️

No Size-Only Load Rating Exists

There is no universal “4×2×1/4 tube holds X pounds.” Capacity depends on span or effective length, support conditions, load pattern, axis orientation, material specification, wall thickness, local slenderness, lateral stability, flexure, shear, compression, connection details and deflection criteria.

Yield strength (50 ksi for Grade C) is a material property, not a member load capacity. For structural use, have a licensed design professional check the member to AISC 360, or use a design tool that does. The beam load calculator is a starting aid only.

Common Rectangular Tube Sizing Mistakes

Quick checks before you order or specify.

📏

Treating HSS dimensions as inside

They are outside dimensions.

📝

Omitting wall thickness

Depth and width alone do not identify a section.

🎯

Calling 4×2 a full spec

Wall and specification are required.

🔄

Reversing depth and width

Depth is the larger dimension.

🔠

Confusing nominal and design wall

They differ by 7 percent for A500.

🧮

Using nominal wall for A500 properties

AISC uses 0.93 t(nom).

🚫

Applying 0.93 to A1085

A1085 uses nominal wall.

📑

Mixing A500 and A1085 tables

Label each row’s specification.

🏭

Mixing structural and A513 tube

Do not assign A500 properties to A513.

□

Treating square and rectangular alike

Their properties differ.

📐

Treating tube as sharp-corner

Real corners are rounded.

⤤

Ignoring corner radii

They change area and inertia.

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Using B – 2t as exact inside

It is an approximation.

⚖️

Using theoretical weight

Published weight is preferred.

📏

Confusing lb/ft with total weight

Multiply by length.

📙

Confusing area with section modulus

Different quantities.

📑

Confusing I with S

S = I / c.

↔️

Confusing Ix and Iy

X-X belongs to the depth.

🔄

Rotating tube unaware

Strong and weak axes swap.

💪

Assuming bigger is stronger

Wall, span and bracing matter.

🧱

Assuming thicker wall solves everything

Buckling and connections can still govern.

📈

Using yield as capacity

Capacity needs a member check.

🚫

Publishing ‘holds X lb’ by size

No such universal value.

📦

Assuming every size is stocked

Check availability.

📦

Assuming every wall exists

Not every wall is made for every size.

📜

Ignoring ASTM grade

Grade sets strength.

🌧️

Ignoring corrosion and exposure

Coatings and exposure matter.

🔗

Ignoring connection capacity

Connections often govern.

📐

Ignoring deflection

Serviceability can control.

📐

Ignoring local slenderness

Thin walls can buckle locally.

💧

Using an HSS table for pipe

Pipe uses NPS and schedule.

📝

Using pipe schedule terms for HSS

Schedules do not apply.

Steel Rectangular Tube FAQs

Thirty common questions, answered with AISC, STI and ASTM information.

What sizes does rectangular steel tubing come in?

Rectangular HSS comes in many outside sizes. Common families are 2×1, 3×2, 4×2, 4×3, 5×3, 6×2, 6×3, 6×4 and 8×4 in., with nominal walls from 1/8 to 5/8 in. depending on size. Availability varies by producer, so check the STI capability tool.

What does HSS4x2x1/4 mean?

It is a rectangular hollow structural section with a nominal 4 in. outside depth, 2 in. outside width and 1/4 in. nominal wall thickness, in AISC’s depth x width x wall format.

Are rectangular tube dimensions inside or outside?

Outside. The depth and width in an HSS designation are overall outside dimensions. The inside opening is smaller because of the wall and the rounded corners.

What is the wall thickness of rectangular steel tubing?

It varies. Common nominal HSS walls are 1/8, 3/16, 1/4, 5/16, 3/8, 1/2 and 5/8 in. (0.125, 0.1875, 0.250, 0.3125, 0.375, 0.500 and 0.625 in.), and some producers list decimal walls such as 0.134 and 0.165 in.

What is design wall thickness?

The wall thickness AISC uses to compute section properties. For ASTM A500 it is 0.93 times the nominal wall; for A1085 it equals the nominal wall.

Why is A500 design wall 0.93 of nominal?

ASTM A500 permits a wall-thickness tolerance of about 10 percent, so AISC design uses 0.93 times nominal. The tube wall is not physically reduced to 93 percent.

Does A1085 use 0.93 wall thickness?

No. A1085 has a minimum thickness tolerance of only -5 percent and a minimum mass tolerance of -3.5 percent, so AISC allows section properties to use the full nominal wall.

What is ASTM A500?

A specification for cold-formed welded and seamless carbon steel structural tubing in rounds and shapes, with a perimeter up to 88 in. and a nominal wall up to 1 in. It is the most common U.S. specification for structural HSS.

What is ASTM A500 Grade C?

The predominant A500 grade for HSS, with a minimum yield strength of 50 ksi and a tensile strength of 62 ksi. These are material strengths, not member load capacities.

What is ASTM A1085?

A specification for cold-formed welded carbon steel HSS with tighter wall and mass tolerances, a 50 ksi minimum yield (70 ksi maximum) and a Charpy V-notch requirement. It is currently less available than A500.

Is rectangular tubing the same as HSS?

Not always. Rectangular HSS is structural tubing made to ASTM A500 or A1085 with published AISC properties. Other rectangular tubing, such as mechanical tubing, can have different standards and properties.

Is mechanical tubing the same as structural HSS?

No. Mechanical tubing is often made to ASTM A513 and can differ in tolerances, materials and corner geometry. Do not assign A500 or A1085 structural properties to it without a proper basis.

What is the difference between rectangular and square HSS?

Square HSS has equal width and depth, so Ix equals Iy. Rectangular HSS has a larger depth than width, so its stiffness differs by axis. Properties are not interchangeable.

How much does 2×1 rectangular tube weigh?

HSS2x1x1/8 weighs 2.20 lb/ft and HSS2x1x3/16 weighs 3.04 lb/ft.

How much does 3×2 rectangular tube weigh?

HSS3x2 weighs 3.90 lb/ft (1/8 in. wall), 5.59 lb/ft (3/16), 7.11 lb/ft (1/4) and 8.45 lb/ft (5/16). The STI HSS3x2x0.134 weighs 4.16 lb/ft.

How much does 4×2 rectangular tube weigh?

HSS4x2 weighs 4.75 lb/ft (1/8 in. wall), 6.87 lb/ft (3/16), 8.81 lb/ft (1/4), 10.58 lb/ft (5/16) and 12.17 lb/ft (3/8).

How much does 6×4 rectangular tube weigh?

HSS6x4 weighs 8.16 lb/ft (1/8 in. wall), 11.97 lb/ft (3/16), 15.62 lb/ft (1/4), 19.08 lb/ft (5/16), 22.37 lb/ft (3/8) and 28.43 lb/ft (1/2).

How do you calculate tube weight?

Use the published weight per foot times the length. An idealized estimate is W = 3.403 x A (lb/ft, with A in square inches), but it overstates the weight of a real rounded-corner HSS, so use published values.

How do you calculate rectangular tube area?

An idealized sharp-corner area is A = 2t(B + H – 2t). For a 4x2x1/4 tube that gives 2.75 in2. Published HSS areas are smaller because of the rounded corners and the design wall.

How do you calculate inside dimensions?

Approximately Hi = H – 2t and Bi = B – 2t. For a 4x2x1/4 tube, about 3.50 x 1.50 in. This is a flat-wall approximation because the inside corners are rounded.

How do you calculate moment of inertia?

For an idealized sharp-corner tube, Ix = (BH3 – bh3)/12 and Iy = (HB3 – hb3)/12 with b = B – 2t and h = H – 2t. For real HSS, use the published AISC or STI values.

What is section modulus?

S = I / c, the moment of inertia divided by the distance to the extreme fiber. For a rectangular tube Sx = 2Ix/H and Sy = 2Iy/B. It indicates elastic bending resistance but is not a load rating.

What is radius of gyration?

r = the square root of I/A. It is used for slenderness and buckling checks and is not the corner radius.

Which way is rectangular tube stronger?

With the larger dimension acting as the depth, because Ix is greater than Iy. For the STI HSS3x2x0.134, Ix = 1.38 in4 versus Iy = 0.733 in4, about 1.88 times. That is a stiffness ratio, not an allowable-load ratio.

Does wall thickness increase strength?

A thicker wall raises area, weight, inertia and section modulus, but not linearly, and it does not by itself solve buckling, connection or deflection limits.

How much weight can rectangular steel tubing hold?

There is no size-only answer. Capacity depends on span or effective length, supports, loading, orientation, steel grade, wall thickness, local slenderness, bracing, shear, compression, connections and deflection limits.

Can rectangular HSS be used as a beam?

Yes, it is widely used as a beam, but it must be designed for the loads and span using AISC provisions. Properties such as Ix and Sx help, but they do not choose the beam for you.

Can rectangular HSS be used as a column?

Yes. Area, rx, ry, effective length and slenderness govern buckling under AISC 360. Have a licensed design professional check the member.

What is the corner radius of HSS?

STI reports a maximum corner radius of 3t for A500 rectangular and square HSS, where t is the wall thickness. The corners are rounded, so the section is not a sharp-corner box.

Are all HSS sizes readily available?

No. STI distinguishes sizes that are regularly produced, produced on demand and not produced, and mill ranges vary by producer. A size in a table is not a stock guarantee.

Standards and References Used

Primary sources behind the values on this page

Reference	What It Covers	Used For
AISC Hollow Structural Sections	HSS definition, designation format, A500 and A1085	Terminology and designation
STI ASTM A500	Grade C strengths, 0.93 design wall, corner radius, availability	A500 data
STI ASTM A1085	A1085 tolerances, CVN and availability	A1085 comparison
STI A500 dimensions and section properties	Published A500 dimensions and properties	HSS3x2x0.134 row and property checks
ASTM A500/A500M-23	Cold-formed welded and seamless carbon steel structural tubing	A500 scope
ASTM A1085/A1085M-22	Cold-formed welded carbon steel HSS	A1085 scope

Section properties on this page follow the AISC/STI design-wall method. For final design, use the current AISC Steel Construction Manual or the STI brochure. Local codes, project specifications and the engineer of record govern structural use.

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