W18x65 — Dimensions, Weight & Section Properties
American wide-flange (W) beam per ASTM A6 / AISC Steel Construction Manual
W18x65 is an American wide-flange beam 18.4 inches (467.4 mm) deep with a 7.59 in (192.8 mm) flange, weighing 65 pounds per foot (96.7 kg/m) — that is what the "65" 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 | 18.4 in (467.4 mm) |
| Flange width bf | 7.59 in (192.8 mm) |
| Web thickness tw | 0.45 in (11.4 mm) |
| Flange thickness tf | 0.75 in (19 mm) |
Weight & Cross-Section
| Weight per foot | 65 lb/ft (96.7 kg/m) |
| 20 ft bar | 1,300 lb |
| 40 ft bar | 2,600 lb |
| Area A | 19.1 in² (123.2 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 1,070 in⁴ (44,537 cm⁴) |
| Section modulus Sx | 117 in³ (1,917 cm³) |
| Radius of gyration rx | 7.49 in |
| Moment of inertia Iy | 54.8 in⁴ (2,281 cm⁴) |
| Section modulus Sy | 14.4 in³ (236 cm³) |
| Radius of gyration ry | 1.69 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| W18x60 | 18.2 × 7.56 | 60 | 984 | 108 | −8 % | −8 % |
| W18x65 (this page) | 18.4 × 7.59 | 65 | 1,070 | 117 | — | — |
| W18x71 | 18.5 × 7.64 | 71 | 1,170 | 127 | +9 % | +9 % |
Deflection example
A simply supported W18x65 spanning 29 ft with a 10 kip point load at midspan deflects 0.28 in (E = 29,000 ksi, Ix = 1,070 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 W18x65 beam weigh?
W18x65 weighs 65 pounds per foot (96.7 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 1,300 lb and a 40 ft bar 2,600 lb.
What are the dimensions of a W18x65?
W18x65 is 18.4 in (467.4 mm) deep with a 7.59 in (192.8 mm) wide flange. The web is 0.45 in thick and the flanges are 0.75 in thick. Note the actual depth differs from the nominal W18 label — always design with the actual value.
What are the dimensions of a W18x65 in mm?
W18x65 is 467.4 mm deep with a 192.8 mm wide flange; the web is 11.4 mm and the flange 19 mm thick. In metric section properties: Ix = 44,537 cm⁴, Sx = 1,917 cm³.
How much does a W18x65 weigh in kg?
96.7 kg per meter. A 6 m bar weighs 580 kg and a 12 m bar 1,161 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a W18x65?
About the strong axis, Ix = 1,070 in⁴ (44,537 cm⁴) with section modulus Sx = 117 in³. About the weak axis, Iy = 54.8 in⁴ and Sy = 14.4 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
W18x65 or W18x71 — what does one size up change?
W18x71 is about 9% heavier (71 vs 65 lb/ft) but about 9% stiffer (Ix 1,170 vs 1,070 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