Aluminum Rectangular Tubing — Sizes, Applications & Cut to Size Guide

Aluminum rectangular tubing is widely used in fabrication because it combines low weight, good corrosion resistance and reliable structural performance in a shape that is easy to cut, drill and assemble. For builders working on fences, gates, pergolas, machine frames or workshop structures, choosing the right aluminum rectangular tubing means looking beyond outer dimensions alone. Section size, wall thickness, span length, connection method and finish all affect how the final structure behaves in real use.

At AluVeno, aluminum profiles are supplied cut to custom length for projects that need clean, repeatable dimensions without unnecessary material waste. This is especially useful when planning modular frames, fence infills, gate structures or machine bases where accuracy matters from the first cut. The most common rectangular sections range from 20x80 mm to 20x200 mm, with different wall thicknesses selected according to stiffness, weight and fastening requirements.

This guide explains the most practical sizes, where each section works best, how to choose wall thickness, and when rectangular tubing is a better choice than square tube or V-SLOT profile.

What is aluminum rectangular tubing?

Aluminum rectangular tubing is a hollow profile with two longer flat faces and two shorter side faces. Compared with round tube, it is easier to align and mount to flat surfaces. Compared with square tube, it offers directional stiffness: the wider face can be oriented to resist bending in the direction where loads are highest. That makes it a practical option for horizontal rails, gate frames, panel supports and long members in lightweight structural assemblies.

In real projects, rectangular tubing is often selected when the designer wants a low-profile shape with more bending resistance than a narrow square tube of similar weight. It also provides clean visual lines, which is one reason it is common in architectural fencing and modern exterior fabrication.

Common aluminum rectangular tubing sizes and where they fit

The right size depends on span, loading, connection detail and appearance. Smaller sections are suitable for trim frames, machine guards and lightweight supports, while larger sections are better for gates, pergolas and load-bearing rails.

Profile size	Typical use	Why it works
20x80 mm	Light frames, machine supports, narrow rails	Slim profile, easy to integrate where space is limited
20x100 mm	Decorative panels, trim structures, lightweight beams	More face width for mounting and visual balance
20x120 mm	Cladding frames, pergola details, infill supports	Useful where a wider visible surface is preferred
20x150 mm	Long rails, larger gate members, façade elements	Improved bending resistance over shorter heights
20x200 mm	Large-span architectural structures, heavy-duty rails	High stiffness in one direction with relatively low mass

These are not the only available dimensions, but they represent a practical range for projects where the 20 mm thickness is maintained and the wider face is used to increase rigidity or create a specific visual effect.

How to choose aluminum rectangular tubing by wall thickness

Wall thickness has a major effect on strength, dent resistance, weldability and screw holding. Two profiles with the same outer dimensions can perform very differently depending on whether the wall is thin or structural-grade.

Wall thickness	Best for	Notes
1.5 mm	Light decorative frames, covers, non-structural elements	Low weight, but less margin for impact and fastening
2.0 mm	General-purpose fabrication, panel frames, moderate spans	Good balance of stiffness, machinability and weight
3.0 mm	Gates, structural rails, high-load welded assemblies	Better for heavy-duty use and repeated mechanical loads

For bolted assemblies, thicker walls generally improve thread engagement and reduce deformation around brackets. For welded structures, thicker sections are usually easier to work with consistently, especially when the component will see movement, wind load or repeated opening cycles, as in gates.

Aluminum rectangular tubing for fencing and gates

In fencing applications, aluminum rectangular tubing is often used for horizontal members, infill frames and gate leaves. The shape sits neatly within modern fence designs and creates a clean linear appearance. For most fence systems, 40x40 mm square profiles are a solid choice for rails because they offer balanced stiffness and straightforward joining. For posts, 80x80 mm square profiles are typically preferred because they provide the stability needed for anchoring, wind resistance and hinge loads.

Where rectangular tubing becomes especially useful is in gate frames and wider decorative spans. A rectangular section can be oriented so that the deeper face resists bending across the opening. For example, if a gate frame needs a horizontal member with improved rigidity but a slimmer visual line than a large square tube, a rectangular profile can be a more efficient solution.

Recommended approach for fence structures

• Use 40x40 mm square profiles for fence rails because they provide a practical balance between stiffness, appearance and ease of fixing panels or slats.
• Use 80x80 mm square profiles for fence and gate posts because they handle anchoring forces and overall structural loads more reliably.
• Use rectangular tubing for gate cross-members, infill frames or design features when directional stiffness or a wider visible face is needed.

This combination usually gives better structural logic than trying to use one profile type everywhere. Posts need torsional and base stiffness, while rails and frame members may benefit from a flatter, more directional shape.

Using aluminum rectangular tubing in CNC and machine frames

Although V-SLOT and T-SLOT profiles are the standard choice for adjustable CNC machines and 3D printer builds, aluminum rectangular tubing still has a place in machine design. It works well as a base beam, support leg, enclosure frame or reinforcement member where slot channels are not required.

A common approach is to use V-SLOT profiles such as 2020, 2040, 2060 or 2080 for motion-related parts, then combine them with rectangular tubing in static sections of the frame. This can reduce complexity while preserving stiffness where it matters. For example, a rectangular profile may be used as a long support beam under a CNC table, while V-SLOT handles linear motion, accessories and modular attachments.

The key advantage here is separation of function: slotted profiles for adjustability, plain tubing for structural economy and clean geometry.

Cut to size guide for aluminum rectangular tubing

Ordering aluminum rectangular tubing cut to size saves fabrication time and improves repeatability, but only if the required dimensions are defined correctly. Before ordering, confirm not just the overall length but also how the profile will be joined and whether end preparation matters.

What to specify

• Profile outer dimension, for example 20x80 mm or 20x150 mm
• Wall thickness
• Exact cut length in millimetres
• Required quantity of each length
• Whether the ends will be welded, capped, drilled or fixed with brackets

Practical tips

• Allow for joint gaps or bracket thickness if the tube sits between posts or side members.
• For visible architectural work, keep all repeated components identical to maintain alignment.
• For welded frames, verify whether final dimensions refer to raw cut parts or finished outside dimensions after assembly.
• For machine structures, check clearance for feet, plates and fasteners before finalizing beam lengths.

A cut-to-size service is particularly useful when ordering multiple profile lengths for a fence, gate or pergola, because it reduces workshop preparation and helps ensure consistent installation on site.

When to choose rectangular tubing vs square tubing or V-SLOT

Profile type	Choose it when	Typical examples
Rectangular tubing	You need directional stiffness or a flatter visual profile	Gate members, wide rails, support beams
Square tubing