W18x46 — Dimensions, Weight & Section Properties
American wide-flange (W) beam per ASTM A6 / AISC Steel Construction Manual
W18x46 is an American wide-flange beam 18.1 inches (459.7 mm) deep with a 6.06 in (153.9 mm) flange, weighing 46 pounds per foot (68.5 kg/m) — that is what the "46" 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 | 18.1 in (459.7 mm) |
| Flange width bf | 6.06 in (153.9 mm) |
| Web thickness tw | 0.36 in (9.1 mm) |
| Flange thickness tf | 0.605 in (15.4 mm) |
Weight & Cross-Section
| Weight per foot | 46 lb/ft (68.5 kg/m) |
| 20 ft bar | 920 lb |
| 40 ft bar | 1,840 lb |
| Area A | 13.5 in² (87.1 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 712 in⁴ (29,636 cm⁴) |
| Section modulus Sx | 78.8 in³ (1,291 cm³) |
| Radius of gyration rx | 7.25 in |
| Moment of inertia Iy | 22.5 in⁴ (937 cm⁴) |
| Section modulus Sy | 7.43 in³ (122 cm³) |
| Radius of gyration ry | 1.29 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| W18x40 | 17.9 × 6.02 | 40 | 612 | 68.4 | −13 % | −14 % |
| W18x46 (this page) | 18.1 × 6.06 | 46 | 712 | 78.8 | — | — |
| W18x50 | 18 × 7.5 | 50 | 800 | 88.9 | +9 % | +12 % |
Deflection example
A simply supported W18x46 spanning 29 ft with a 10 kip point load at midspan deflects 0.43 in (E = 29,000 ksi, Ix = 712 in⁴). The L/360 serviceability limit for this span is 0.97 in — the shape passes this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a W18x46 beam weigh?
W18x46 weighs 46 pounds per foot (68.5 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 920 lb and a 40 ft bar 1,840 lb.
What are the dimensions of a W18x46?
W18x46 is 18.1 in (459.7 mm) deep with a 6.06 in (153.9 mm) wide flange. The web is 0.36 in thick and the flanges are 0.61 in thick. Note the actual depth differs from the nominal W18 label — always design with the actual value.
What are the dimensions of a W18x46 in mm?
W18x46 is 459.7 mm deep with a 153.9 mm wide flange; the web is 9.1 mm and the flange 15.4 mm thick. In metric section properties: Ix = 29,636 cm⁴, Sx = 1,291 cm³.
How much does a W18x46 weigh in kg?
68.5 kg per meter. A 6 m bar weighs 411 kg and a 12 m bar 821 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a W18x46?
About the strong axis, Ix = 712 in⁴ (29,636 cm⁴) with section modulus Sx = 78.8 in³. About the weak axis, Iy = 22.5 in⁴ and Sy = 7.43 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
W18x46 or W18x50 — what does one size up change?
W18x50 is about 9% heavier (50 vs 46 lb/ft) but about 12% stiffer (Ix 800 vs 712 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