HSS3x3x5/16 — Dimensions, Weight & Section Properties
Hollow structural section per ASTM A500 / AISC Steel Construction Manual
HSS3x3x5/16 is an American hollow structural section (HSS) 3×3 inches (76.2×76.2 mm) with a nominal 0.313 in wall, weighing 10.58 pounds per foot (15.7 kg/m). Section properties below are the AISC published values, computed with the A500 design wall thickness of 0.93×nominal — with metric equivalents alongside.
Typical uses: columns, braces, truss members, equipment frames, and architectural steel — closed sections excel in compression and torsion and take paint beautifully. For a quick stiffness check, see the deflection example below or open the beam calculator with your own span and load.
Dimensions
| Height h | 3 in (76.2 mm) |
| Width b | 3 in (76.2 mm) |
| Nominal wall t | 0.313 in (8 mm) |
| Design wall (0.93t) | 0.291 in (7.4 mm) |
Weight & Cross-Section
| Weight per foot | 10.58 lb/ft (15.7 kg/m) |
| 20 ft bar | 212 lb |
| 40 ft bar | 423 lb |
| Area A | 2.94 in² (19 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 3.45 in⁴ (144 cm⁴) |
| Section modulus Sx | 2.3 in³ (38 cm³) |
| Radius of gyration rx | 1.08 in |
| Moment of inertia Iy | 3.45 in⁴ (144 cm⁴) |
| Section modulus Sy | 2.3 in³ (38 cm³) |
| Radius of gyration ry | 1.08 in |
Compared with the neighbouring sizes
| Shape | h × b (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| HSS3x3x1/4 | 3 × 3 | 8.81 | 3.02 | 2.01 | −17 % | −12 % |
| HSS3x3x5/16 (this page) | 3 × 3 | 10.58 | 3.45 | 2.3 | — | — |
| HSS3x3x3/8 | 3 × 3 | 12.17 | 3.78 | 2.52 | +15 % | +10 % |
Deflection example
A simply supported HSS3x3x5/16 spanning 5 ft with a 10 kip point load at midspan deflects 0.45 in (E = 29,000 ksi, Ix = 3.45 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 HSS3x3x5/16 tube weigh?
HSS3x3x5/16 weighs 10.58 pounds per foot (15.7 kg/m). A 20 ft bar weighs 212 lb and a 40 ft bar 423 lb.
What are the dimensions of a HSS3x3x5/16?
HSS3x3x5/16 is 3×3 in (76.2×76.2 mm) outside, with a nominal wall of 0.313 in. Note that A500 tolerances put the design wall at 0.93×nominal (0.291 in) — the section properties listed already account for this.
What are the dimensions of a HSS3x3x5/16 in mm?
HSS3x3x5/16 is 76.2×76.2 mm outside with a nominal wall of 8 mm. In metric section properties: Ix = 144 cm⁴, Sx = 38 cm³.
How much does a HSS3x3x5/16 weigh in kg?
15.7 kg per meter. A 6 m bar weighs 94 kg and a 12 m bar 189 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a HSS3x3x5/16?
About the strong axis, Ix = 3.45 in⁴ (144 cm⁴) with section modulus Sx = 2.3 in³. About the weak axis, Iy = 3.45 in⁴ and Sy = 2.3 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
HSS3x3x5/16 or HSS3x3x3/8 — what does one size up change?
HSS3x3x3/8 is about 15% heavier (12.17 vs 10.58 lb/ft) but about 10% stiffer (Ix 3.78 vs 3.45 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