W18x55 is a wide flange steel beam that is 18.1 in deep with a 7.53 in flange and weighs 55 lb/ft (82 kg/m). Its metric designation is W460x82. All values below come from the AISC Shapes Database v16.0.
W18x55 Dimensions
| Property | Symbol | Imperial | Metric |
|---|---|---|---|
| Nominal weight | W | 55 lb/ft | 82 kg/m |
| Cross-sectional area | A | 16.2 in² | 10,500 mm² |
| Depth | d | 18.1 in | 460 mm |
| Flange width | bf | 7.53 in | 191 mm |
| Web thickness | tw | 0.39 in | 9.91 mm |
| Flange thickness | tf | 0.63 in | 16 mm |
| Distance to web toe of fillet (design) | kdes | 1.03 in | 26.2 mm |
| Distance to web toe of fillet (detailing) | kdet | 1.3125 in | 33.3 mm |
| Web center line to flange toe of fillet | k1 | 0.8125 in | 20.6 mm |
| Distance between web toes of fillets | T | 15.5 in | 394 mm |
| Workable gage (inner holes) | WGi | 3.5 in | 88.9 mm |
W18x55 Section Properties
| Property | Symbol | Imperial | Metric |
|---|---|---|---|
| Moment of inertia, x-axis | Ix | 890 in⁴ | 370 ×10⁶ mm⁴ |
| Elastic section modulus, x-axis | Sx | 98.3 in³ | 1,610 ×10³ mm³ |
| Plastic section modulus, x-axis | Zx | 112 in³ | 1,840 ×10³ mm³ |
| Radius of gyration, x-axis | rx | 7.41 in | 188 mm |
| Moment of inertia, y-axis | Iy | 44.9 in⁴ | 18.7 ×10⁶ mm⁴ |
| Elastic section modulus, y-axis | Sy | 11.9 in³ | 195 ×10³ mm³ |
| Plastic section modulus, y-axis | Zy | 18.5 in³ | 303 ×10³ mm³ |
| Radius of gyration, y-axis | ry | 1.67 in | 42.4 mm |
| Torsional constant | J | 1.66 in⁴ | 691 ×10³ mm⁴ |
| Warping constant | Cw | 3,430 in⁶ | 921 ×10⁹ mm⁶ |
| Effective radius of gyration | rts | 2 in | 50.8 mm |
| Distance between flange centroids | ho | 17.5 in | 444 mm |
| Flange slenderness | bf/2tf | 5.98 | 5.98 |
| Web slenderness | h/tw | 41.1 | 41.1 |
W18x55 Weight Calculator
Enter a length to get the total weight of a W18x55 beam. A 20 ft length weighs 1,100 lb.
Uses the AISC nominal weight: 55 lb/ft (82 kg/m).
Beams Similar to W18x55
| Shape | Weight (lb/ft) | Depth (in) | Flange width (in) |
|---|---|---|---|
| W18x60 | 60 | 18.2 | 7.56 |
| W18x50 | 50 | 18 | 7.5 |
| W18x46 | 46 | 18.1 | 6.06 |
See every W18 size in the W18 beam sizes chart, or compare all shapes in the wide flange beam sizes chart. Working in millimetres? W18x55 is listed as W460x82 in the metric wide flange beam sizes chart.
W18x55 FAQ
What does W18x55 mean?
W means wide flange. The first number (18) is the nominal depth in inches, and the second number (55) is the weight in pounds per foot. The actual depth of W18x55 is 18.1 in. How to read steel beam sizes.
How much does a W18x55 beam weigh?
W18x55 weighs 55 lb per foot (82 kg per meter). A 20 ft beam weighs about 1,100 lb. Use the calculator above for any length.
What is the metric equivalent of W18x55?
The metric (SI) designation is W460x82: 460 mm deep with a 191 mm flange and 82 kg/m.
How far can a W18x55 beam span?
Span depends on the load, support conditions, deflection limits and local building code, so it cannot be read from a size table. A licensed structural engineer must size any beam that carries a load.
Source: AISC Shapes Database v16.0, consistent with the AISC Steel Construction Manual, 16th Edition. Last updated: September 2026.
This page is reference information only and is not engineering advice. Do not use it for a specific design without verification by a licensed engineer or architect. Full disclaimer.