Steel Angle (Angle Iron): Equal & Unequal Leg Sizes

Angle iron and how to read an angle size

Steel angle, also called angle iron or structural angle, is a hot-⁠rolled L-section with two legs at a right angle. Under ASTM A6, angles with a leg of 3 in. or more are structural-size shapes, and smaller ones such as L2×2×1/4 are bar-size shapes. The table covers both.

AISC designations give the legs and thickness in inches, long leg first. Legs are measured on the outside, from the heel (the corner) to the toe (the tip of the leg), and both legs have the same thickness. Read L4×3×3/8 like this:

• L: steel angle
• 4: long leg, 4 in.
• 3: short leg, 3 in.
• 3/8: thickness of both legs, 3/8 in.
• Mixed fractions: L3-1/2×2-1/2×1/4 has a 3-1/2 in. long leg, and L12×12×1-3/8 has legs 1-3/8 in. thick

Equal-⁠leg vs. unequal-⁠leg angles

Equal-leg angles have two legs of the same length. The table lists 61, from L2×2×1/8 to L12×12×1-3/8, with legs of 2, 2-1/2, 3, 3-1/2, 4, 5, 6, 8, 10 and 12 in. Section properties about the two leg axes are the same.

Unequal-leg angles have one long leg and one short leg. The table lists 76, from L2-1/2×1-1/2×3/16 to L8×6×1. Drawings show which way the long leg turns: LLV for long leg vertical, LLH for long leg horizontal.

The choice changes weight too: L4×4×3/8 is 9.8 lb/ft and L4×3×3/8 is 8.5 lb/ft. Change a leg, a thickness or the orientation only with your engineer’s review.

Where steel angles are used

Typical uses for steel angle in structural and miscellaneous steel:

• Bracing: X-bracing, knee braces and struts in frames and dunnage
• Clips: clip angles for beam connections and attachments, cut and punched or drilled to the shop drawings
• Lintels: over door, window and masonry openings
• Frames: equipment frames and skids
• Supports: mechanical and electrical supports and secondary framing for equipment platforms

Grades: ASTM A36 and A572 Grade 50

We supply steel angles in ASTM A36 and A572 Grade 50, and other grades on request. A36 is a carbon steel with a 36 ksi minimum yield and 58 to 80 ksi tensile strength. A572 Grade 50, a high-strength low-alloy grade, raises the minimum yield to 50 ksi, with 65 ksi minimum tensile.

Much of the angle on the market comes from heats that meet both A36 and A572 Grade 50, and the mill test report shows when it does. The grade on your drawings governs, and ASTM A6 sets the dimensions and tolerances.

Processing and delivery

Angles ship in random lengths or cut and punched to your drawings. Without shop drawings, our detailing team can prepare them and the cut list.

Within California we deliver angles to your shop or job site; for jobs in Texas, Arizona, Nevada and nationwide, they ship to the job site. Every load is quoted on its own. Processing options:

• Cut to length, including mitered cuts
• Holes punched or drilled; slots laser or plasma cut
• Section-rolled into arcs and rings for canopies, arches and roof framing
• Hot-⁠dip galvanizing, ASTM A123
• Piece-mark tags and bundling, with mill test reports and heat-number traceability

Channel, flat bar or cold-⁠formed profiles

For framing, lintels and equipment, C and MC channel is on the steel channels page. Flat bar for straps, stiffeners and base plates is on the structural steel page.

Roll-⁠formed C, Z and U profiles from 20 gauge to ¼ in. are under cold-⁠formed profiles. For a leg size the table does not list, we can press-brake form angles from sheet and plate in single pieces up to 26 ft long, for your engineer to review against the rolled section.