L3x3x5/16 — Dimensions, Weight & Section Properties
Steel angle (L-shape) per ASTM A6 / AISC Steel Construction Manual
L3x3x5/16 is a hot-rolled steel angle with equal 3 in (76.2 mm) legs, 0.313 in thick, weighing 6.1 pounds per foot (9.1 kg/m). All values below are the standard AISC published section properties, with metric equivalents alongside.
Typical uses: bracing, lintels, shelf supports, frames, and connection material. Angles are weak about their minor axis — long unbraced angles need lateral restraint. For a quick check, see the deflection example below or open the beam calculator.
Dimensions
| Long leg | 3 in (76.2 mm) |
| Equal leg | 3 in (76.2 mm) |
| Thickness t | 0.313 in (8 mm) |
Weight & Cross-Section
| Weight per foot | 6.1 lb/ft (9.1 kg/m) |
| 20 ft bar | 122 lb |
| 40 ft bar | 244 lb |
| Area A | 1.78 in² (11.5 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 1.5 in⁴ (62 cm⁴) |
| Section modulus Sx | 0.7 in³ (11 cm³) |
| Radius of gyration rx | 0.92 in |
| Moment of inertia Iy | 1.5 in⁴ (62 cm⁴) |
| Section modulus Sy | 0.7 in³ (11 cm³) |
| Radius of gyration ry | 0.92 in |
Compared with the neighbouring sizes
| Shape | legs (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| L3x3x1/4 | 3 × 3 | 4.9 | 1.23 | 0.57 | −20 % | −18 % |
| L3x3x5/16 (this page) | 3 × 3 | 6.1 | 1.5 | 0.7 | — | — |
| L3x3x3/8 | 3 × 3 | 7.2 | 1.75 | 0.83 | +18 % | +17 % |
Deflection example
A simply supported L3x3x5/16 spanning 5 ft with a 10 kip point load at midspan deflects 1.03 in (E = 29,000 ksi, Ix = 1.5 in⁴). The L/360 serviceability limit for this span is 0.17 in — the shape does NOT pass this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a L3x3x5/16 angle weigh?
L3x3x5/16 weighs 6.1 pounds per foot (9.1 kg/m). A 20 ft bar weighs 122 lb and a 40 ft bar 244 lb.
What are the dimensions of a L3x3x5/16?
L3x3x5/16 has two equal 3 in (76.2 mm) legs, both 0.313 in thick. Angle legs are measured outside-to-outside, and both legs share the same thickness.
What are the dimensions of a L3x3x5/16 in mm?
L3x3x5/16 has two equal 76.2 mm legs, 8 mm thick. In metric section properties: Ix = 62 cm⁴, Sx = 11 cm³.
How much does a L3x3x5/16 weigh in kg?
9.1 kg per meter. A 6 m bar weighs 54 kg and a 12 m bar 109 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a L3x3x5/16?
About the strong axis, Ix = 1.5 in⁴ (62 cm⁴) with section modulus Sx = 0.7 in³. About the weak axis, Iy = 1.5 in⁴ and Sy = 0.7 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
L3x3x5/16 or L3x3x3/8 — what does one size up change?
L3x3x3/8 is about 18% heavier (7.2 vs 6.1 lb/ft) but about 17% stiffer (Ix 1.75 vs 1.5 in⁴). Going one step up within the same depth group is usually the cheapest way to cut deflection.
Values are entered from the governing standard’s published tables and cross-checked programmatically against its mass and section formulas before publication. Spotted an error? Write to advertising@metalabout.net — verified corrections ship within days. About