W12×40 vs W12×45
A side-by-side comparison of two AISC wide-flange beams, 16th Edition. Detailing dimensions to the nearest 1/16 in.
W12×45 is the heavier section at 45 lb per foot, versus 40 for W12×40 (5 lb/ft more).
Both are nominally 12 in. deep.
W12×45 has the greater bending strength: section modulus Sx of 57.7 in³ versus 51.5, about 12% more.
| Property | W12×40 | W12×45 |
|---|---|---|
| Weight | 40 lb/ft | 45 lb/ft |
| Depth (d) | 12" | 12" |
| Flange width (bf) | 8" | 8" |
| Web thickness (tw) | 5/16" | 5/16" |
| Flange thickness (tf) | 1/2" | 9/16" |
| Area (A) | 11.7 in² | 13.1 in² |
| Moment of inertia (Ix) | 307 in⁴ | 348 in⁴ |
| Section modulus (Sx) | 51.5 in³ | 57.7 in³ |
| Plastic modulus (Zx) | 57 in³ | 64.2 in³ |
Open W12×40 in the interactive size chart →
Full detail: W12×40 · W12×45. Verify critical dimensions against the current AISC Steel Construction Manual before fabrication.
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