Steel beam properties (W shapes)
Section properties for common AISC wide-flange (W) steel beams: depth, weight, area, moment of inertia, and section modulus. Use it to compare beams for stiffness (deflection) and strength (bending) when sizing a span.
Wide-flange (W) beams, strong-axis properties
| Section | Depth (in) | Weight (lb/ft) | Area (in²) | Ix (in⁴) | Sx (in³) |
|---|---|---|---|---|---|
| W8x10 | 7.89 | 10 | 2.96 | 30.8 | 7.81 |
| W8x18 | 8.14 | 18 | 5.26 | 61.9 | 15.2 |
| W10x12 | 9.87 | 12 | 3.54 | 53.8 | 10.9 |
| W10x22 | 10.17 | 22 | 6.49 | 118 | 23.2 |
| W12x14 | 11.91 | 14 | 4.16 | 88.6 | 14.9 |
| W12x26 | 12.22 | 26 | 7.65 | 204 | 33.4 |
| W14x22 | 13.74 | 22 | 6.49 | 199 | 29.0 |
| W14x30 | 13.84 | 30 | 8.85 | 291 | 42.0 |
| W16x26 | 15.69 | 26 | 7.68 | 301 | 38.4 |
| W16x36 | 15.86 | 36 | 10.6 | 448 | 56.5 |
| W18x35 | 17.70 | 35 | 10.3 | 510 | 57.6 |
| W21x44 | 20.66 | 44 | 13.0 | 843 | 81.6 |
| W24x55 | 23.57 | 55 | 16.2 | 1350 | 114 |
W shapes are named by nominal depth and weight per foot: a W12x26 is about 12 inches deep and weighs 26 lb/ft. Ix is the moment of inertia, which governs deflection (stiffness); Sx is the section modulus, which governs bending strength. Larger values carry more load with less sag. Values are strong-axis (bending about the X axis).
Sizing a beam for a span?
Use these Ix and Sx values with the engineering calculators to check beam deflection and bending stress.
Moment of inertia vs section modulus
Both describe how a cross-section resists bending, but they answer different questions. Moment of inertia Ix sets stiffness: a higher Ix means less deflection under the same load. Section modulus Sx sets strength: a higher Sx means lower bending stress, so the beam can carry more before it yields. Deep beams score high on both because material far from the center is most effective.
Why depth beats weight
Putting material farther from the neutral axis raises Ix and Sx sharply, so a deeper beam is far stiffer and stronger than a shallow one of the same weight. That is why a W12x26 carries much more than a W8x28 despite weighing about the same: depth, not just pounds of steel, drives capacity.
FAQ
What does W12x26 mean?
A wide-flange beam about 12 inches deep weighing 26 pounds per foot. The first number is nominal depth, the second is weight per foot.
What is the difference between Ix and Sx?
Ix is the moment of inertia, which controls deflection (stiffness). Sx is the section modulus, which controls bending strength. Ix divided by half the depth gives Sx.
How do I choose a beam size?
Find the load and span, calculate the required section modulus for strength and moment of inertia for an acceptable deflection, then pick the lightest beam that meets both.