W40x149 — Dimensions, Weight & Section Properties
American wide-flange (W) beam per ASTM A6 / AISC Steel Construction Manual
W40x149 is an American wide-flange beam 38.2 inches (970.3 mm) deep with a 11.8 in (299.7 mm) flange, weighing 149 pounds per foot (221.7 kg/m) — that is what the "149" 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 | 38.2 in (970.3 mm) |
| Flange width bf | 11.8 in (299.7 mm) |
| Web thickness tw | 0.63 in (16 mm) |
| Flange thickness tf | 0.83 in (21.1 mm) |
Weight & Cross-Section
| Weight per foot | 149 lb/ft (221.7 kg/m) |
| 20 ft bar | 2,980 lb |
| 40 ft bar | 5,960 lb |
| Area A | 43.8 in² (282.6 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 9,800 in⁴ (407,905 cm⁴) |
| Section modulus Sx | 513 in³ (8,407 cm³) |
| Radius of gyration rx | 15 in |
| Moment of inertia Iy | 229 in⁴ (9,532 cm⁴) |
| Section modulus Sy | 38.8 in³ (636 cm³) |
| Radius of gyration ry | 2.29 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| W40x149 (this page) | 38.2 × 11.8 | 149 | 9,800 | 513 | — | — |
| W40x167 | 38.6 × 11.8 | 167 | 11,600 | 600 | +12 % | +18 % |
Deflection example
A simply supported W40x149 spanning 61 ft with a 10 kip point load at midspan deflects 0.29 in (E = 29,000 ksi, Ix = 9,800 in⁴). The L/360 serviceability limit for this span is 2.03 in — the shape passes this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a W40x149 beam weigh?
W40x149 weighs 149 pounds per foot (221.7 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 2,980 lb and a 40 ft bar 5,960 lb.
What are the dimensions of a W40x149?
W40x149 is 38.2 in (970.3 mm) deep with a 11.8 in (299.7 mm) wide flange. The web is 0.63 in thick and the flanges are 0.83 in thick. Note the actual depth differs from the nominal W40 label — always design with the actual value.
What are the dimensions of a W40x149 in mm?
W40x149 is 970.3 mm deep with a 299.7 mm wide flange; the web is 16 mm and the flange 21.1 mm thick. In metric section properties: Ix = 407,905 cm⁴, Sx = 8,407 cm³.
How much does a W40x149 weigh in kg?
221.7 kg per meter. A 6 m bar weighs 1,330 kg and a 12 m bar 2,661 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a W40x149?
About the strong axis, Ix = 9,800 in⁴ (407,905 cm⁴) with section modulus Sx = 513 in³. About the weak axis, Iy = 229 in⁴ and Sy = 38.8 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
W40x149 or W40x167 — what does one size up change?
W40x167 is about 12% heavier (167 vs 149 lb/ft) but about 18% stiffer (Ix 11,600 vs 9,800 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