W16x31 is a wide flange steel beam that is 15.9 in deep with a 5.53 in flange and weighs 31 lb/ft (46.1 kg/m). Its metric designation is W410x46.1. All values below come from the AISC Shapes Database v16.0.
W16x31 Dimensions
| Property | Symbol | Imperial | Metric |
|---|---|---|---|
| Nominal weight | W | 31 lb/ft | 46.1 kg/m |
| Cross-sectional area | A | 9.13 in² | 5,890 mm² |
| Depth | d | 15.9 in | 404 mm |
| Flange width | bf | 5.53 in | 140 mm |
| Web thickness | tw | 0.275 in | 6.99 mm |
| Flange thickness | tf | 0.44 in | 11.2 mm |
| Distance to web toe of fillet (design) | kdes | 0.842 in | 21.4 mm |
| Distance to web toe of fillet (detailing) | kdet | 1.125 in | 28.6 mm |
| Web center line to flange toe of fillet | k1 | 0.75 in | 19.1 mm |
| Distance between web toes of fillets | T | 13.625 in | 346 mm |
| Workable gage (inner holes) | WGi | 3.5 in | 88.9 mm |
W16x31 Section Properties
| Property | Symbol | Imperial | Metric |
|---|---|---|---|
| Moment of inertia, x-axis | Ix | 375 in⁴ | 156 ×10⁶ mm⁴ |
| Elastic section modulus, x-axis | Sx | 47.2 in³ | 773 ×10³ mm³ |
| Plastic section modulus, x-axis | Zx | 54 in³ | 885 ×10³ mm³ |
| Radius of gyration, x-axis | rx | 6.41 in | 163 mm |
| Moment of inertia, y-axis | Iy | 12.4 in⁴ | 5.16 ×10⁶ mm⁴ |
| Elastic section modulus, y-axis | Sy | 4.49 in³ | 73.6 ×10³ mm³ |
| Plastic section modulus, y-axis | Zy | 7.03 in³ | 115 ×10³ mm³ |
| Radius of gyration, y-axis | ry | 1.17 in | 29.7 mm |
| Torsional constant | J | 0.461 in⁴ | 192 ×10³ mm⁴ |
| Warping constant | Cw | 739 in⁶ | 198 ×10⁹ mm⁶ |
| Effective radius of gyration | rts | 1.42 in | 36.1 mm |
| Distance between flange centroids | ho | 15.5 in | 394 mm |
| Flange slenderness | bf/2tf | 6.28 | 6.28 |
| Web slenderness | h/tw | 51.6 | 51.6 |
W16x31 Weight Calculator
Enter a length to get the total weight of a W16x31 beam. A 20 ft length weighs 620 lb.
Uses the AISC nominal weight: 31 lb/ft (46.1 kg/m).
Beams Similar to W16x31
See every W16 size in the W16 beam sizes chart, or compare all shapes in the wide flange beam sizes chart.
W16x31 FAQ
What does W16x31 mean?
W means wide flange. The first number (16) is the nominal depth in inches, and the second number (31) is the weight in pounds per foot. The actual depth of W16x31 is 15.9 in. How to read steel beam sizes.
How much does a W16x31 beam weigh?
W16x31 weighs 31 lb per foot (46.1 kg per meter). A 20 ft beam weighs about 620 lb. Use the calculator above for any length.
What is the metric equivalent of W16x31?
The metric (SI) designation is W410x46.1: 404 mm deep with a 140 mm flange and 46.1 kg/m.
How far can a W16x31 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.