W8x40 is a wide flange steel beam that is 8.25 in deep with an 8.07 in flange and weighs 40 lb/ft (59 kg/m). Its metric designation is W200x59. All values below come from the AISC Shapes Database v16.0.
W8x40 Dimensions
| Property | Symbol | Imperial | Metric |
|---|---|---|---|
| Nominal weight | W | 40 lb/ft | 59 kg/m |
| Cross-sectional area | A | 11.7 in² | 7,550 mm² |
| Depth | d | 8.25 in | 210 mm |
| Flange width | bf | 8.07 in | 205 mm |
| Web thickness | tw | 0.36 in | 9.14 mm |
| Flange thickness | tf | 0.56 in | 14.2 mm |
| Distance to web toe of fillet (design) | kdes | 0.954 in | 24.2 mm |
| Distance to web toe of fillet (detailing) | kdet | 1.25 in | 31.8 mm |
| Web center line to flange toe of fillet | k1 | 0.8125 in | 20.6 mm |
| Distance between web toes of fillets | T | 5.75 in | 146 mm |
| Workable gage (inner holes) | WGi | 5.5 in | 140 mm |
W8x40 Section Properties
| Property | Symbol | Imperial | Metric |
|---|---|---|---|
| Moment of inertia, x-axis | Ix | 146 in⁴ | 60.8 ×10⁶ mm⁴ |
| Elastic section modulus, x-axis | Sx | 35.5 in³ | 582 ×10³ mm³ |
| Plastic section modulus, x-axis | Zx | 39.8 in³ | 652 ×10³ mm³ |
| Radius of gyration, x-axis | rx | 3.53 in | 89.7 mm |
| Moment of inertia, y-axis | Iy | 49.1 in⁴ | 20.4 ×10⁶ mm⁴ |
| Elastic section modulus, y-axis | Sy | 12.2 in³ | 200 ×10³ mm³ |
| Plastic section modulus, y-axis | Zy | 18.5 in³ | 303 ×10³ mm³ |
| Radius of gyration, y-axis | ry | 2.04 in | 51.8 mm |
| Torsional constant | J | 1.12 in⁴ | 466 ×10³ mm⁴ |
| Warping constant | Cw | 726 in⁶ | 195 ×10⁹ mm⁶ |
| Effective radius of gyration | rts | 2.31 in | 58.7 mm |
| Distance between flange centroids | ho | 7.69 in | 195 mm |
| Flange slenderness | bf/2tf | 7.21 | 7.21 |
| Web slenderness | h/tw | 17.6 | 17.6 |
W8x40 Weight Calculator
Enter a length to get the total weight of a W8x40 beam. A 20 ft length weighs 800 lb.
Uses the AISC nominal weight: 40 lb/ft (59 kg/m).
Beams Similar to W8x40
| Shape | Weight (lb/ft) | Depth (in) | Flange width (in) |
|---|---|---|---|
| W8x35 | 35 | 8.12 | 8.02 |
| W8x48 | 48 | 8.5 | 8.11 |
| W8x31 | 31 | 8 | 8 |
See every W8 size in the W8 beam sizes chart, or compare all shapes in the wide flange beam sizes chart. Working in millimetres? W8x40 is listed as W200x59 in the metric wide flange beam sizes chart.
W8x40 FAQ
What does W8x40 mean?
W means wide flange. The first number (8) is the nominal depth in inches, and the second number (40) is the weight in pounds per foot. The actual depth of W8x40 is 8.25 in. How to read steel beam sizes.
How much does a W8x40 beam weigh?
W8x40 weighs 40 lb per foot (59 kg per meter). A 20 ft beam weighs about 800 lb. Use the calculator above for any length.
What is the metric equivalent of W8x40?
The metric (SI) designation is W200x59: 210 mm deep with a 205 mm flange and 59 kg/m.
How far can a W8x40 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.