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Aluminium rectangular tube sizes, wall and cut length

Updated: October 2026

You have a gap in a shelf or a light frame, and the listing offers three numbers, an imperial line, and a technical field that may not describe the same bar. Aluminium rectangular tube sizes, in these five amazon.co.uk cuts, are mill-finish lengths of 800 mm or 1,000 mm, not 5 m or 6 m stockholder bars. Read on 16 October 2026. A qualifying purchase through our links can earn a commission at no extra cost to you. Write the outside sizes, the wall, the length, and the temper before you pay. The ranked rows stay on the [aluminium rectangular tube comparison](/hub/rods-and-pipes/aluminium-rectangular-tube).

You have a gap in a shelf or a light frame, and the listing offers three numbers, an imperial line, and a technical field that may not describe the same bar.

Our top picks

Fabal Aluminium Fabal 30 × 15 × 1.3 mm, 800 mm

Best overall

Fabal Aluminium Fabal 30 × 15 × 1.3 mm, 800 mm
6.6/10about £12.53
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Fabal Aluminium Fabal 30 × 15 × 1.3 mm, 1 m

Rank 2

Fabal Aluminium Fabal 30 × 15 × 1.3 mm, 1 m
7.8/10about £13.15
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Aluminium Online Aluminium Online 30 × 20 × 2 mm

Best value

Aluminium Online Aluminium Online 30 × 20 × 2 mm
5.2/10about £11.00
View offer
On this page
  1. 1.What the three numbers mean
  2. 2.Metric line, imperial line, and the internal hole
  3. 3.Alloy, temper, and finish
  4. 4.Length, and what this amazon set cannot supply
  5. 5.Write the specification before you pay

What the three numbers mean

A rectangular tube size is two outside faces and a wall. The Aluminium Online titles follow that pattern: 30 × 20 × 2 mm at £11.00, 40 × 20 × 2 mm at £15.85, and 60 × 40 × 3 mm at £21.59, each a stated 1,000 mm. On the 800 mm Fabal page, at £12.53, the outside-diameter field stores 1.3 mm, which is the wall. On model RH060x40x3 the technical block also stores item form Sheet and 6 × 4 × 0.1 cm. If the parcel is that sheet, section 11 of the Consumer Rights Act 2015 says goods must match the description.

Metric line, imperial line, and the internal hole

Fabal says the imperial figures are approximate and that the metric sizes are the exact ones. The cut tolerance is about ±2 mm, so an 800 mm order can arrive near 798 mm or 802 mm. That allowance does not fill an 850 mm opening. Outside minus twice the wall is only geometry. For 40 × 20 × 2 mm that sum is about 36 mm by 16 mm, and it is still not a caliper reading. None of these five titles says seamless. If a liner must fit, measure the bore after the burr is off, on the how to cut aluminium box section page.
Fabal Aluminium Fabal 30 × 15 × 1.3 mm, 800 mm

Testsieger

Fabal Aluminium Fabal 30 × 15 × 1.3 mm, 800 mm
6.6/10about £12.53
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Alloy, temper, and finish

6063 is a magnesium-silicon extrusion alloy. T6 means it was solution heat-treated and then artificially aged. BS EN 755-2 sets properties by alloy, temper, and thickness, and this page does not copy those tables. Both Fabal bars, £12.53 for 800 mm and £13.15 for 1,000 mm, state 6063-T6 and mill finish. The three Aluminium Online bars state neither. Do not upgrade them to T6 or call them 6082. Mill finish is bare metal, not a coating in the box. None of the five listings includes screws, brackets, or end caps. If you need a mill certificate, leave this set.

Length, and what this amazon set cannot supply

Every kept bar stops at 1,000 mm, except the shorter Fabal at 800 mm. A typical garden gate is wider than 1 m. LA Metals lists 5 m and 6 m rectangular box, including 30 × 20 × 2 mm, 40 × 20 × 2 mm, and 60 × 40 × 3 mm. If the frame must carry a person, a roof, a stair, or a floor, a 1 m craft bar does not answer Approved Document A. If you are still choosing the metal, use the aluminium box section vs steel box section page.

Write the specification before you pay

Write five lines and keep them with the order: wide face, narrow face, wall, length, and alloy with temper. A stated temper might read 30 × 15 × 1.3 mm, 1,000 mm, 6063-T6, mill finish. The £11.00 bar should read 30 × 20 × 2 mm, 1,000 mm, alloy not stated. When the tube arrives, check both faces against the title, not against the outside-diameter field. If 30 × 15 mm and T6 fit a frame under 1 m, the conditional pick is on the best aluminium rectangular tube page.

Common questions

What does 30 × 15 × 1.3 actually mean?
It is the wide outside face, the narrow outside face, and the wall, in millimetres: 30 mm by 15 mm with a 1.3 mm wall, at £12.53 for 800 mm or £13.15 for 1,000 mm. It is not an outside diameter. The shorter Fabal’s technical block stores 1.3 mm in that field, so measure both faces when the bar arrives.
Is the imperial line on the packet the size to order?
No. Fabal says the imperial figures are approximate and the metric sizes are exact. Order the metric line that matches your opening, and allow about ±2 mm on those cut lengths. An inch line on the packet is a rounded label, not a second size.
Why is the internal hole smaller than the title?
The title is the outside size. The wall occupies both sides, and the corners are radiused, which these titles do not state. Outside minus twice the wall is a sketch. For 30 × 20 × 2 mm that sketch is about 26 mm by 16 mm. If a cap or a liner must fit, measure the bore after you have filed the cut edge.
Is 6063 the same as 6063-T6?
No. 6063 names the alloy. T6 names the temper: solution heat-treated, then artificially aged. BS EN 755-2 treats those as different rows, and this page does not copy the table. The two Fabal bars state 6063-T6. The Aluminium Online bars state neither, so you cannot promote them to T6, and you cannot call them 6082.
Why does a rectangular listing have an outside-diameter field?
The template is built for round tube, and these pages still fill it. On the 800 mm Fabal the field stores 1.3 mm, the wall. On the 1,000 mm Fabal it stores 30 mm, one face of the rectangle. Neither figure is a diameter for a round sleeve. Read the two outside sizes in the title, then confirm them with a rule.
Is 800 mm or 1,000 mm long enough for a gate?
Often it is not. A typical garden gate is wider than 1 m, and a doorway is wider than the 800 mm Fabal. Joining two cuts makes the joint the weak point. Buy a longer bar from a stockholder when the opening is wider than 1 m.

Related pages

Aluminium box section for outdoor frames

Aluminium rectangular tube

Best aluminium rectangular tube for a short light frame

How to cut aluminium box section with a metal blade

Aluminium box section vs steel for a light UK frame

Sources

Public UK sources and amazon.co.uk listings from the category digest, checked on 16 October 2026. Shelf prices and star lines can change after that date.

  1. Consumer Rights Act 2015 (retrieved 16 October 2026)
  2. Consumer Rights Act 2015, section 9 (satisfactory quality) (retrieved 16 October 2026)
  3. HSE: welding (retrieved 16 October 2026)
  4. HSE: COSHH basics (retrieved 16 October 2026)
  5. Approved Document A: structure (retrieved 16 October 2026)
  6. Using the UKCA marking (retrieved 16 October 2026)
  7. BS EN 755-2: mechanical properties of extruded aluminium (retrieved 16 October 2026)