Angle Iron Sizes, Weights & Uses: The Complete UK Guide

Angle iron — also called steel angle or mild steel L-section — is one of the most widely used structural steel profiles in the UK. Its right-angle shape gives strength in two directions while staying easy to cut, drill and weld, which is why it turns up in everything from shelving brackets to structural frames and lintels. This guide covers the standard angle iron sizes and weights, how to work out the weight of any size, what grade to specify, and how angle iron compares to box section and channel — with a free calculator to price up your job.

Angle Iron Weight Calculator

Enter the leg sizes, thickness and length to get the weight per metre and total weight. For equal angle, enter the same value for both legs; for unequal angle, enter the long and short leg.

What Is Angle Iron?

Angle iron is hot-rolled steel formed into an L-shaped cross-section with two legs at 90 degrees. “Angle iron”, “steel angle” and “L-section” all mean the same thing. It comes in two forms: equal angle, where both legs are the same length (e.g. 50 x 50mm), and unequal angle, where one leg is longer than the other (e.g. 100 x 65mm). Equal angle is the general-purpose choice for frames, brackets and fabrication; unequal angle is used where you need more strength or a wider fixing face on one side. Most UK angle iron is supplied in structural S275 grade mild steel to BS EN 10025-2, in a mill finish.

Equal Angle Iron Sizes & Weights

Standard equal angle sizes and approximate weights, in kg per metre and per 6m length:

Size (mm)	Weight (kg/m)	Per 6m length
20 x 20 x 3	0.87	5.2 kg
25 x 25 x 3	1.11	6.7 kg
30 x 30 x 3	1.34	8.0 kg
40 x 40 x 4	2.39	14.3 kg
40 x 40 x 5	2.94	17.6 kg
40 x 40 x 6	3.49	20.9 kg
50 x 50 x 5	3.73	22.4 kg
50 x 50 x 6	4.43	26.6 kg
50 x 50 x 8	5.78	34.7 kg
60 x 60 x 6	5.37	32.2 kg
60 x 60 x 8	7.03	42.2 kg
70 x 70 x 6	6.31	37.9 kg
70 x 70 x 8	8.29	49.7 kg
75 x 75 x 6	6.78	40.7 kg
75 x 75 x 8	8.92	53.5 kg
80 x 80 x 8	9.55	57.3 kg
90 x 90 x 8	10.80	64.8 kg
90 x 90 x 10	13.34	80.0 kg
100 x 100 x 8	12.06	72.4 kg
100 x 100 x 10	14.91	89.5 kg
120 x 120 x 10	18.05	108.3 kg
150 x 150 x 10	22.76	136.6 kg

Unequal Angle Iron Sizes & Weights

Common unequal angle (long leg x short leg x thickness) sizes and approximate weights:

Size (mm)	Weight (kg/m)	Per 6m length
40 x 25 x 4	1.92	11.5 kg
50 x 30 x 5	2.94	17.6 kg
65 x 50 x 6	5.13	30.8 kg
75 x 50 x 6	5.60	33.6 kg
80 x 60 x 7	7.31	43.9 kg
100 x 65 x 8	9.86	59.2 kg
100 x 75 x 8	10.49	62.9 kg
125 x 75 x 8	12.06	72.4 kg
150 x 75 x 10	16.88	101.3 kg
150 x 90 x 10	18.05	108.3 kg

How to Calculate Angle Iron Weight

The weight of steel angle is worked out from its cross-sectional area and the density of steel (7,850 kg/m³). The quick formula used across the trade is:

Weight (kg/m) = (A + B − t) × t × 0.00785

where A and B are the two leg lengths in mm and t is the thickness in mm. For equal angle, A and B are the same, so it simplifies to (2A − t) × t × 0.00785. For example, a 50 x 50 x 6mm equal angle weighs (100 − 6) × 6 × 0.00785 = 4.43 kg/m. Multiply by the length to get the total — a 6m length is about 26.6 kg. To weigh up other profiles too, use our metal weight calculator, which covers plate, sheet, bar, tube, box and angle across steel, stainless and aluminium.

What Is Angle Iron Used For?

Angle iron is a workshop and site staple. Typical uses include structural frames and supports, gate and railing frames, shelving and racking, lintels over openings, brackets and cleats, trailer and vehicle bodywork, agricultural structures, bracing and cross-members, edge and corner protection, and machine bases. The L-profile resists bending in two planes while leaving flat faces for bolting or welding, which is what makes it so versatile.

Angle Iron vs Box Section vs Channel

Angle iron, box section and channel are the three go-to fabrication sections, each suited to different jobs. Angle iron gives strength in two directions with open, easy-to-fix faces — best for brackets, frames and bracing. Box section (SHS/RHS) is a closed hollow profile with high strength-to-weight and a clean look — best for gates, posts and load-bearing frames. Channel (C/U section) has a deep web with an open face for seating other components — best for runners, purlins and edge beams. Many fabrications combine all three.

Cutting, Drilling & Welding Angle Iron

S275 angle iron cuts, drills and welds with standard metalworking tools — an angle grinder, chop saw or bandsaw for cutting, and MIG or arc welding for joining. It is supplied in a mill finish (black, with mill scale), so clean the surface back to bright metal before welding or painting. Cut ends and drilled holes expose bare steel; protect them if the finished part will be used outdoors.

Galvanised vs Mild Steel Angle Iron

Plain mild steel angle iron will rust if left untreated outdoors, so for exposed or damp work choose galvanised steel angle, which is hot-dip zinc coated to BS EN ISO 1461 for decades of corrosion resistance without painting. For indoor or painted work, mild steel angle is the more economical choice. See our galvanised steel guide for how the coating works.

Buy Angle Iron at Rackerman

Rackerman supplies UK-stock mild steel angle iron in 6m lengths, cut to size on request, with fast UK delivery:

• Mild Steel Equal Angle (angle iron) 6m — S275, 20x20mm to 150x150mm
• Mild Steel Unequal Angle — S275 rolled L-section
• Galvanised Steel Angle 6m — for outdoor use
• Full metal sections range — box, channel, bar, tube and more

Frequently Asked Questions

Is angle iron the same as steel angle?

Yes. Angle iron, steel angle and mild steel L-section all describe the same hot-rolled product — an L-shaped steel section with two legs at 90 degrees. “Angle iron” is the traditional trade name; “steel angle” is the technical term.

What sizes does angle iron come in?

Equal angle typically runs from 20 x 20mm up to 150 x 150mm, in thicknesses from 3mm to 10mm+. Unequal angle covers sizes such as 40 x 25mm up to 150 x 90mm and larger. Rackerman stocks equal angle from 20 x 20mm to 150 x 150mm in 6m lengths.

How much does angle iron weigh?

Weight depends on the leg size and thickness. As examples, 50 x 50 x 6mm weighs about 4.43 kg/m, 75 x 75 x 8mm about 8.92 kg/m and 100 x 100 x 10mm about 14.91 kg/m. Use the formula (A + B − t) × t × 0.00785, or the calculator above, for any size.

What grade is angle iron?

Most UK angle iron is S275 mild steel to BS EN 10025-2, a general-purpose structural grade that is weldable, drillable and easy to fabricate. Higher-strength S355 is available for demanding structural work.

Can angle iron be cut to size?

Yes. Angle iron is supplied in stock lengths (usually 6m) and cuts easily on site with an angle grinder, chop saw or bandsaw. Rackerman also offers cut-to-size on request — contact us with your lengths before ordering.

What is the difference between equal and unequal angle?

Equal angle has two legs of the same length and is used for general frames, brackets and fabrication. Unequal angle has one longer leg, giving more strength or a wider fixing face in one direction — useful for lintels, beams and edge sections.

Will angle iron rust?

Plain mild steel angle iron will rust outdoors if left untreated. For exposed use, choose galvanised angle or paint/prime the steel. Indoors or where it will be painted, mild steel angle is fine.