W6x9 — Dimensions, Weight & Section Properties
American wide-flange (W) beam per ASTM A6 / AISC Steel Construction Manual
W6x9 is an American wide-flange beam 5.9 inches (149.9 mm) deep with a 3.94 in (100.1 mm) flange, weighing 9 pounds per foot (13.4 kg/m) — that is what the "9" in the designation means. All values below are the standard AISC published section properties used in US structural design, with metric equivalents alongside.
Typical uses: floor and roof framing, columns, headers, and general steel construction. For a quick stiffness check, see the deflection example below or open the beam calculator with your own span and load.
Dimensions
| Depth d | 5.9 in (149.9 mm) |
| Flange width bf | 3.94 in (100.1 mm) |
| Web thickness tw | 0.17 in (4.3 mm) |
| Flange thickness tf | 0.215 in (5.5 mm) |
Weight & Cross-Section
| Weight per foot | 9 lb/ft (13.4 kg/m) |
| 20 ft bar | 180 lb |
| 40 ft bar | 360 lb |
| Area A | 2.68 in² (17.3 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 16.4 in⁴ (683 cm⁴) |
| Section modulus Sx | 5.56 in³ (91 cm³) |
| Radius of gyration rx | 2.47 in |
| Moment of inertia Iy | 2.2 in⁴ (92 cm⁴) |
| Section modulus Sy | 1.11 in³ (18 cm³) |
| Radius of gyration ry | 0.91 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| W6x9 (this page) | 5.9 × 3.94 | 9 | 16.4 | 5.56 | — | — |
| W6x12 | 6.03 × 4 | 12 | 22.1 | 7.31 | +33 % | +35 % |
Deflection example
A simply supported W6x9 spanning 9 ft with a 10 kip point load at midspan deflects 0.55 in (E = 29,000 ksi, Ix = 16.4 in⁴). The L/360 serviceability limit for this span is 0.3 in — the shape does NOT pass this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a W6x9 beam weigh?
W6x9 weighs 9 pounds per foot (13.4 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 180 lb and a 40 ft bar 360 lb.
What are the dimensions of a W6x9?
W6x9 is 5.9 in (149.9 mm) deep with a 3.94 in (100.1 mm) wide flange. The web is 0.17 in thick and the flanges are 0.22 in thick. Note the actual depth differs from the nominal W6 label — always design with the actual value.
What are the dimensions of a W6x9 in mm?
W6x9 is 149.9 mm deep with a 100.1 mm wide flange; the web is 4.3 mm and the flange 5.5 mm thick. In metric section properties: Ix = 683 cm⁴, Sx = 91 cm³.
How much does a W6x9 weigh in kg?
13.4 kg per meter. A 6 m bar weighs 80 kg and a 12 m bar 161 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a W6x9?
About the strong axis, Ix = 16.4 in⁴ (683 cm⁴) with section modulus Sx = 5.56 in³. About the weak axis, Iy = 2.2 in⁴ and Sy = 1.11 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
W6x9 or W6x12 — what does one size up change?
W6x12 is about 33% heavier (12 vs 9 lb/ft) but about 35% stiffer (Ix 22.1 vs 16.4 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