W12x40 is a wide flange steel beam that is 11.9 in deep with a 8.01 in flange and weighs 40 lb/ft (60 kg/m). Its metric designation is W310x60. All values below come from the AISC Shapes Database v16.0.
W12x40 Dimensions
| Property | Symbol | Imperial | Metric |
|---|---|---|---|
| Nominal weight | W | 40 lb/ft | 60 kg/m |
| Cross-sectional area | A | 11.7 in² | 7,550 mm² |
| Depth | d | 11.9 in | 302 mm |
| Flange width | bf | 8.01 in | 203 mm |
| Web thickness | tw | 0.295 in | 7.49 mm |
| Flange thickness | tf | 0.515 in | 13.1 mm |
| Distance to web toe of fillet (design) | kdes | 1.02 in | 25.9 mm |
| Distance to web toe of fillet (detailing) | kdet | 1.375 in | 34.9 mm |
| Web center line to flange toe of fillet | k1 | 0.875 in | 22.2 mm |
| Distance between web toes of fillets | T | 9.25 in | 235 mm |
| Workable gage (inner holes) | WGi | 5.5 in | 140 mm |
W12x40 Section Properties
| Property | Symbol | Imperial | Metric |
|---|---|---|---|
| Moment of inertia, x-axis | Ix | 307 in⁴ | 128 ×10⁶ mm⁴ |
| Elastic section modulus, x-axis | Sx | 51.5 in³ | 844 ×10³ mm³ |
| Plastic section modulus, x-axis | Zx | 57 in³ | 934 ×10³ mm³ |
| Radius of gyration, x-axis | rx | 5.13 in | 130 mm |
| Moment of inertia, y-axis | Iy | 44.1 in⁴ | 18.4 ×10⁶ mm⁴ |
| Elastic section modulus, y-axis | Sy | 11 in³ | 180 ×10³ mm³ |
| Plastic section modulus, y-axis | Zy | 16.8 in³ | 275 ×10³ mm³ |
| Radius of gyration, y-axis | ry | 1.94 in | 49.3 mm |
| Torsional constant | J | 0.906 in⁴ | 377 ×10³ mm⁴ |
| Warping constant | Cw | 1,440 in⁶ | 387 ×10⁹ mm⁶ |
| Effective radius of gyration | rts | 2.21 in | 56.1 mm |
| Distance between flange centroids | ho | 11.4 in | 290 mm |
| Flange slenderness | bf/2tf | 7.77 | 7.77 |
| Web slenderness | h/tw | 33.6 | 33.6 |
W12x40 Weight Calculator
Enter a length to get the total weight of a W12x40 beam. A 20 ft length weighs 800 lb.
Uses the AISC nominal weight: 40 lb/ft (60 kg/m).
Beams Similar to W12x40
| Shape | Weight (lb/ft) | Depth (in) | Flange width (in) |
|---|---|---|---|
| W12x45 | 45 | 12.1 | 8.05 |
| W12x35 | 35 | 12.5 | 6.56 |
| W12x50 | 50 | 12.2 | 8.08 |
See every W12 size in the W12 beam sizes chart, or compare all shapes in the wide flange beam sizes chart.
W12x40 FAQ
What does W12x40 mean?
W means wide flange. The first number (12) is the nominal depth in inches, and the second number (40) is the weight in pounds per foot. The actual depth of W12x40 is 11.9 in. How to read steel beam sizes.
How much does a W12x40 beam weigh?
W12x40 weighs 40 lb per foot (60 kg per meter). A 20 ft beam weighs about 800 lb. Use the calculator above for any length.
What is the metric equivalent of W12x40?
The metric (SI) designation is W310x60: 302 mm deep with a 203 mm flange and 60 kg/m.
How far can a W12x40 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.