W18x283 — Dimensions, Weight & Section Properties
American wide-flange (W) beam per ASTM A6 / AISC Steel Construction Manual
W18x283 is an American wide-flange beam 21.9 inches (556.3 mm) deep with a 11.9 in (302.3 mm) flange, weighing 283 pounds per foot (421.2 kg/m) — that is what the "283" 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 | 21.9 in (556.3 mm) |
| Flange width bf | 11.9 in (302.3 mm) |
| Web thickness tw | 1.4 in (35.6 mm) |
| Flange thickness tf | 2.5 in (63.5 mm) |
Weight & Cross-Section
| Weight per foot | 283 lb/ft (421.2 kg/m) |
| 20 ft bar | 5,660 lb |
| 40 ft bar | 11,320 lb |
| Area A | 83.3 in² (537.4 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 6,170 in⁴ (256,814 cm⁴) |
| Section modulus Sx | 565 in³ (9,259 cm³) |
| Radius of gyration rx | 8.61 in |
| Moment of inertia Iy | 704 in⁴ (29,303 cm⁴) |
| Section modulus Sy | 118 in³ (1,934 cm³) |
| Radius of gyration ry | 2.91 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| W18x258 | 21.5 × 11.8 | 258 | 5,510 | 514 | −9 % | −11 % |
| W18x283 (this page) | 21.9 × 11.9 | 283 | 6,170 | 565 | — | — |
| W18x311 | 22.3 × 12 | 311 | 6,970 | 624 | +10 % | +13 % |
Deflection example
A simply supported W18x283 spanning 35 ft with a 10 kip point load at midspan deflects 0.09 in (E = 29,000 ksi, Ix = 6,170 in⁴). The L/360 serviceability limit for this span is 1.17 in — the shape passes this quick check.
Calculate with your own span and load →
Frequently asked questions
How much does a W18x283 beam weigh?
W18x283 weighs 283 pounds per foot (421.2 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 5,660 lb and a 40 ft bar 11,320 lb.
What are the dimensions of a W18x283?
W18x283 is 21.9 in (556.3 mm) deep with a 11.9 in (302.3 mm) wide flange. The web is 1.4 in thick and the flanges are 2.5 in thick. Note the actual depth differs from the nominal W18 label — always design with the actual value.
What are the dimensions of a W18x283 in mm?
W18x283 is 556.3 mm deep with a 302.3 mm wide flange; the web is 35.6 mm and the flange 63.5 mm thick. In metric section properties: Ix = 256,814 cm⁴, Sx = 9,259 cm³.
How much does a W18x283 weigh in kg?
421.2 kg per meter. A 6 m bar weighs 2,527 kg and a 12 m bar 5,054 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a W18x283?
About the strong axis, Ix = 6,170 in⁴ (256,814 cm⁴) with section modulus Sx = 565 in³. About the weak axis, Iy = 704 in⁴ and Sy = 118 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
W18x283 or W18x311 — what does one size up change?
W18x311 is about 10% heavier (311 vs 283 lb/ft) but about 13% stiffer (Ix 6,970 vs 6,170 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