W18x86 — Dimensions, Weight & Section Properties
American wide-flange (W) beam per ASTM A6 / AISC Steel Construction Manual
W18x86 is an American wide-flange beam 18.4 inches (467.4 mm) deep with a 11.1 in (281.9 mm) flange, weighing 86 pounds per foot (128 kg/m) — that is what the "86" 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 | 11.1 in (281.9 mm) |
| Web thickness tw | 0.48 in (12.2 mm) |
| Flange thickness tf | 0.77 in (19.6 mm) |
Weight & Cross-Section
| Weight per foot | 86 lb/ft (128 kg/m) |
| 20 ft bar | 1,720 lb |
| 40 ft bar | 3,440 lb |
| Area A | 25.3 in² (163.2 cm²) |
Section Properties (strong / weak axis)
| Moment of inertia Ix | 1,530 in⁴ (63,683 cm⁴) |
| Section modulus Sx | 166 in³ (2,720 cm³) |
| Radius of gyration rx | 7.77 in |
| Moment of inertia Iy | 175 in⁴ (7,284 cm⁴) |
| Section modulus Sy | 31.6 in³ (518 cm³) |
| Radius of gyration ry | 2.63 in |
Compared with the neighbouring sizes
| Shape | d × bf (in) | lb/ft | Ix (in⁴) | Sx (in³) | Δ weight | Δ Ix |
|---|---|---|---|---|---|---|
| W18x76 | 18.2 × 11 | 76 | 1,330 | 146 | −12 % | −13 % |
| W18x86 (this page) | 18.4 × 11.1 | 86 | 1,530 | 166 | — | — |
| W18x97 | 18.6 × 11.1 | 97 | 1,750 | 188 | +13 % | +14 % |
Deflection example
A simply supported W18x86 spanning 29 ft with a 10 kip point load at midspan deflects 0.2 in (E = 29,000 ksi, Ix = 1,530 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 W18x86 beam weigh?
W18x86 weighs 86 pounds per foot (128 kg/m). The number after the "x" in the designation is always the weight in lb/ft. A 20 ft bar weighs 1,720 lb and a 40 ft bar 3,440 lb.
What are the dimensions of a W18x86?
W18x86 is 18.4 in (467.4 mm) deep with a 11.1 in (281.9 mm) wide flange. The web is 0.48 in thick and the flanges are 0.77 in thick. Note the actual depth differs from the nominal W18 label — always design with the actual value.
What are the dimensions of a W18x86 in mm?
W18x86 is 467.4 mm deep with a 281.9 mm wide flange; the web is 12.2 mm and the flange 19.6 mm thick. In metric section properties: Ix = 63,683 cm⁴, Sx = 2,720 cm³.
How much does a W18x86 weigh in kg?
128 kg per meter. A 6 m bar weighs 768 kg and a 12 m bar 1,536 kg — handy when ordering US shapes from metric suppliers.
What is the moment of inertia of a W18x86?
About the strong axis, Ix = 1,530 in⁴ (63,683 cm⁴) with section modulus Sx = 166 in³. About the weak axis, Iy = 175 in⁴ and Sy = 31.6 in³. Use the beam deflection calculator to turn these into deflection and stress for your span and load.
W18x86 or W18x97 — what does one size up change?
W18x97 is about 13% heavier (97 vs 86 lb/ft) but about 14% stiffer (Ix 1,750 vs 1,530 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