W18x175 — Dimensions, Weight & Section Properties
American wide-flange (W) beam per ASTM A6 / AISC Steel Construction Manual
W18x175 is an American wide-flange beam 20 inches (508 mm) deep with a 11.4 in (289.6 mm) flange, weighing 175 pounds per foot (260.4 kg/m) — that is what the "175" 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 | 20 in (508 mm) |
| Flange width bf | 11.4 in (289.6 mm) |
| Web thickness tw | 0.89 in (22.6 mm) |
| Flange thickness tf | 1.59 in (40.4 mm) |
Weight & Cross-Section
| Weight per foot | 175 lb/ft (260.4 kg/m) |
| 20 ft bar | 3,500 lb |
| 40 ft bar | 7,000 lb |
| Area A | 51.4 in² (331.6 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 3,450 in⁴ (143,599 cm⁴) |
| Section modulus Sx | 344 in³ (5,637 cm³) |
| Radius of gyration rx | 8.2 in |
| Moment of inertia Iy | 391 in⁴ (16,275 cm⁴) |
| Section modulus Sy | 68.8 in³ (1,127 cm³) |
| Radius of gyration ry | 2.76 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| W18x158 | 19.7 × 11.3 | 158 | 3,060 | 310 | −10 % | −11 % |
| W18x175 (this page) | 20 × 11.4 | 175 | 3,450 | 344 | — | — |
| W18x192 | 20.4 × 11.5 | 192 | 3,870 | 380 | +10 % | +12 % |
Deflection example
A simply supported W18x175 spanning 32 ft with a 10 kip point load at midspan deflects 0.12 in (E = 29,000 ksi, Ix = 3,450 in⁴). The L/360 serviceability limit for this span is 1.07 in — the shape passes this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a W18x175 beam weigh?
W18x175 weighs 175 pounds per foot (260.4 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 3,500 lb and a 40 ft bar 7,000 lb.
What are the dimensions of a W18x175?
W18x175 is 20 in (508 mm) deep with a 11.4 in (289.6 mm) wide flange. The web is 0.89 in thick and the flanges are 1.59 in thick. Note the actual depth differs from the nominal W18 label — always design with the actual value.
What are the dimensions of a W18x175 in mm?
W18x175 is 508 mm deep with a 289.6 mm wide flange; the web is 22.6 mm and the flange 40.4 mm thick. In metric section properties: Ix = 143,599 cm⁴, Sx = 5,637 cm³.
How much does a W18x175 weigh in kg?
260.4 kg per meter. A 6 m bar weighs 1,563 kg and a 12 m bar 3,125 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a W18x175?
About the strong axis, Ix = 3,450 in⁴ (143,599 cm⁴) with section modulus Sx = 344 in³. About the weak axis, Iy = 391 in⁴ and Sy = 68.8 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
W18x175 or W18x192 — what does one size up change?
W18x192 is about 10% heavier (192 vs 175 lb/ft) but about 12% stiffer (Ix 3,870 vs 3,450 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