W33×291 vs W33×318
A side-by-side comparison of two AISC wide-flange beams, 16th Edition. Detailing dimensions to the nearest 1/16 in.
W33×318 is the heavier section at 318 lb per foot, versus 291 for W33×291 (27 lb/ft more).
Both are nominally 33 in. deep.
W33×318 has the greater bending strength: section modulus Sx of 1110 in³ versus 1020, about 9% more.
| Property | W33×291 | W33×318 |
|---|---|---|
| Weight | 291 lb/ft | 318 lb/ft |
| Depth (d) | 34 7/8" | 35 1/8" |
| Flange width (bf) | 15 7/8" | 16" |
| Web thickness (tw) | 15/16" | 1 1/16" |
| Flange thickness (tf) | 1 3/4" | 1 7/8" |
| Area (A) | 85.6 in² | 93.7 in² |
| Moment of inertia (Ix) | 17700 in⁴ | 19500 in⁴ |
| Section modulus (Sx) | 1020 in³ | 1110 in³ |
| Plastic modulus (Zx) | 1160 in³ | 1270 in³ |
Open W33×291 in the interactive size chart →
Full detail: W33×291 · W33×318. Verify critical dimensions against the current AISC Steel Construction Manual before fabrication.
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