Angle (L-shape) properties
Section properties for equal-leg structural steel angles: weight, area, moment of inertia, and section modulus. Angles are the workhorses of bracing, brackets, frames, and lintels.
Equal-leg angles (L)
| Size | Weight (lb/ft) | Area (in²) | Ix = Iy (in⁴) | Sx (in³) |
|---|---|---|---|---|
| L2x2x1/4 | 3.19 | 0.944 | 0.346 | 0.244 |
| L2x2x3/8 | 4.7 | 1.36 | 0.476 | 0.348 |
| L3x3x1/4 | 4.9 | 1.44 | 1.23 | 0.569 |
| L3x3x3/8 | 7.2 | 2.11 | 1.75 | 0.825 |
| L3x3x1/2 | 9.4 | 2.75 | 2.20 | 1.06 |
| L4x4x1/4 | 6.6 | 1.93 | 3.00 | 1.03 |
| L4x4x3/8 | 9.8 | 2.86 | 4.32 | 1.50 |
| L4x4x1/2 | 12.8 | 3.75 | 5.52 | 1.96 |
| L6x6x3/8 | 14.9 | 4.36 | 15.4 | 3.51 |
| L6x6x1/2 | 19.6 | 5.77 | 19.9 | 4.59 |
An angle is named by its two leg lengths and thickness, so L4x4x1/2 has two 4 inch legs that are 1/2 inch thick. For equal-leg angles Ix equals Iy about the geometric axes. Note that an angle is strongest about its diagonal (the Z axis) and weakest perpendicular to it, so single angles loaded in bending also tend to twist and deflect sideways.
Comparing against beams or channels?
See the Steel Beam Properties Chart and the Channel Properties Chart.
Where angles are used
Angles are everywhere in steelwork: cross-bracing in frames, shelf and ledge supports, brackets, lintels over openings, and the chords of light trusses. Their two legs make them easy to bolt or weld to other members in two planes, and they are cheap and widely stocked, which is why they appear in so much general fabrication.
Single vs double angles
A single angle is unsymmetrical and twists when bent, so its real capacity is below what the simple section properties suggest. Pairing two angles back to back, as a double angle, creates a symmetric T-shaped member that bends without twisting and is the standard choice for truss members and braces carrying real load.
FAQ
What does L4x4x1/2 mean?
An equal-leg angle with two 4 inch legs, each 1/2 inch thick. The first two numbers are leg lengths, the third is thickness.
Why is Ix equal to Iy for an equal-leg angle?
Because the two legs are the same length, the section is symmetric about the 45-degree line, making the moments of inertia about the horizontal and vertical axes equal.
Can a single angle be used as a beam?
Only for light loads. A single angle twists and deflects sideways when bent, so for real bending a double angle or a beam is used instead.