W21×68 vs W24×68
A side-by-side comparison of two AISC wide-flange beams, 16th Edition. Detailing dimensions to the nearest 1/16 in.
W21×68 and W24×68 both weigh 68 lb per foot, so the choice comes down to depth and stiffness rather than weight.
W24×68 is the deeper section at a nominal 24 in., versus 21 in.
W24×68 has the greater bending strength: section modulus Sx of 154 in³ versus 140, about 10% more.
| Property | W21×68 | W24×68 |
|---|---|---|
| Weight | 68 lb/ft | 68 lb/ft |
| Depth (d) | 21 1/8" | 23 3/4" |
| Flange width (bf) | 8 1/4" | 9" |
| Web thickness (tw) | 7/16" | 7/16" |
| Flange thickness (tf) | 11/16" | 9/16" |
| Area (A) | 20 in² | 20.1 in² |
| Moment of inertia (Ix) | 1480 in⁴ | 1830 in⁴ |
| Section modulus (Sx) | 140 in³ | 154 in³ |
| Plastic modulus (Zx) | 160 in³ | 177 in³ |
Open W21×68 in the interactive size chart →
Full detail: W21×68 · W24×68. Verify critical dimensions against the current AISC Steel Construction Manual before fabrication.
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