W8x18 weight and dimensions
26.6 kg/m · 18.00 lb/ft
W8x18 is a 207 mm deep beam with a 133 mm flange, 5.84 mm web and 8.38 mm flange thickness. It weighs 26.6 kg per metre (18.00 lb/ft). It belongs to the W-shape wide flange beam series, American (AISC / ASTM A6).
W8x18 weight calculator
Weight of standard lengths
| Pieces | 20 ft each (lb) | 40 ft each (lb) |
|---|---|---|
| 1 | 357.5 | 715.0 |
| 5 | 1,787.4 | 3,574.9 |
| 10 | 3,574.9 | 7,149.7 |
| 20 | 7,149.7 | 14,299.5 |
| 50 | 17,874.4 | 35,748.7 |
Pieces per ton
| 20 ft lengths per short ton (2,000 lb) | 5.6 |
| 40 ft lengths per short ton (2,000 lb) | 2.8 |
| Length per ton | 111.9 ft |
Useful for converting a tonnage order into a number of bars.
Surface area for painting
| Per metre of length | 0.922 m²/m |
| Per foot of length | 3.02 ft²/ft |
| Per tonne of steel | 34.7 m²/t |
| A 12 m length | 11.06 m² |
Outside perimeter × length, all faces (AISC perimeter PB). Use it to estimate paint, primer, fireproofing or galvanizing quantities.
Cross-section
Drawn to scale. Dimensions in mm.
Dimensions
| Depth h | 207 mm | 8.150 in |
| Flange width b | 133 mm | 5.236 in |
| Web thickness tw | 5.84 mm | 0.230 in |
| Flange thickness tf | 8.38 mm | 0.330 in |
| Root radius r | 7.6 mm | 0.299 in |
| Mass | 26.6 kg/m | 18.00 lb/ft |
Section properties
| Property | Value | Unit |
|---|---|---|
| Area | 33.90 | cm² |
| Moment of inertia Ix | 2,580 | cm⁴ |
| Moment of inertia Iy | 332 | cm⁴ |
| Elastic modulus Zx | 249 | cm³ |
| Elastic modulus Zy | 49.80 | cm³ |
| Plastic modulus Zpx | 279 | cm³ |
| Plastic modulus Zpy | 76.40 | cm³ |
| Radius of gyration rx | 8.71 | cm |
| Radius of gyration ry | 3.12 | cm |
| Torsion constant J | 7.16 | cm⁴ |
Equivalent sections in other standards
The closest sections by depth and weight. They are not direct substitutes: check bending, buckling and connection details before swapping one for another.
W8x18 and its closest equivalents, drawn over each other at the same scale.
| Section | Standard | Depth (mm) | kg/m | Weight vs W8x18 |
|---|---|---|---|---|
| W8x18 | AISC | 207 | 26.6 | — |
| ISWB 200 | IS | 200 | 28.80 | +8.3% |
| ISMB 200 | IS | 200 | 24.17 | -9.1% |
| IPE 220 | EN | 220 | 26.20 | -1.5% |
| IPE 200 | EN | 200 | 22.36 | -15.9% |
W8 series weights
Next lighter: W8x15 (22.5 kg/m). Next heavier: W8x21 (31.3 kg/m).
Stiffness and strength per kilogram
The elastic section modulus Zx governs bending strength. Dividing it by the weight shows how efficiently each size uses its steel: higher is better when weight is the cost driver.
| Section | kg/m | Ix (cm⁴) | Zx (cm³) | Zx per kg/m |
|---|---|---|---|---|
| W8x10 | 15.00 | 1,280 | 128.0 | 8.53 |
| W8x13 | 19.30 | 1,650 | 162.0 | 8.39 |
| W8x15 | 22.50 | 2,000 | 193.0 | 8.58 |
| W8x18 | 26.60 | 2,580 | 249.0 | 9.36 |
| W8x21 | 31.30 | 3,130 | 298.0 | 9.52 |
| W8x24 | 35.90 | 3,440 | 342.0 | 9.53 |
| W8x28 | 41.70 | 4,080 | 398.0 | 9.54 |
Full table: W-shape (wide flange) beam chart (PDF).
How the weight is calculated
Mass per metre = cross-sectional area × density of steel = 33.90 cm² × 0.785 kg/(cm²·m) = 26.61 kg/m.
Rolled sections are made to a nominal mass, and the actual mass can differ by a few percent within the tolerances of ASTM A6. For purchasing, invoicing by weight or checking deliveries, use the producer's stated mass.
Typical uses
Beams of this shape are used as floor and roof beams, lintels, crane girders and frame members, where bending about the strong axis governs.
Frequently asked questions
What is the weight of W8x18 per metre?
W8x18 weighs 26.6 kg/m, which is 18.00 lb/ft.
How much does a 6 m or 12 m length of W8x18 weigh?
A 6 m length weighs about 159.6 kg and a 12 m length about 319.2 kg.
What is the equivalent of W8x18 in other standards?
By depth and weight the closest match is ISWB 200 (28.8 kg/m, 200 mm deep). Check section properties before substituting one for the other.
Source: AISC Shapes Database v16.0. Values are nominal; verify with the producer before ordering.