W8×18 wide-flange beam

Detailing dimensions and section properties from the AISC Shapes Database, 16th Edition. Values are shown to the nearest 1/16 in. as they appear on a shop drawing.

W8×18 measures 8 1/8 in. deep with a 5 1/4 in. flange, on a 1/4 in. web and 5/16 in. flanges.

At 18 lb per foot it is one of the 13 W8 sizes, which run from 10 to 67 lb/ft.

For strong-axis bending its section modulus is Sx = 15.2 in³ and its moment of inertia Ix = 61.9 in⁴, with a plastic modulus Zx = 17 in³.

Detailing dimensions

Depth (d)8 1/8"
Flange width (bf)5 1/4"
Web thickness (tw)1/4"
Flange thickness (tf)5/16"
k (detailing)13/16"
Workable gage (g)2 3/4"

Section properties

Weight18 lb/ft
Area (A)5.26 in²
Ix61.9 in⁴
Sx15.2 in³
Zx17 in³
rx3.43 in
Iy7.97 in⁴
Sy3.04 in³
Zy4.66 in³
ry1.23 in
J0.172 in⁴

Other W8 sizes

Same nominal size, different weight — useful when you are checking a substitution or a lighter section.

W8×10W8×13W8×15W8×21W8×24W8×28W8×31W8×35W8×40W8×48W8×58W8×67

All W8 sizes and dimensions →

Similar weight wide-flange beams

Comparable 18 lb/ft sections in other wide-flange beam sizes.

W10×1717 lb/ft · Sx 16.2 in³W12×1919 lb/ft · Sx 21.3 in³W10×1919 lb/ft · Sx 18.8 in³W5×1919 lb/ft · Sx 10.2 in³W12×1616 lb/ft · Sx 17.1 in³W6×1616 lb/ft · Sx 10.2 in³W5×1616 lb/ft · Sx 8.55 in³W6×2020 lb/ft · Sx 13.4 in³

Compare W8×18 with a nearby size

W8×15 vs W8×18W8×18 vs W8×21

Detailing values are rounded to the nearest 1/16 in. per the AISC Steel Construction Manual. Verify critical dimensions against the current Manual before fabrication. Need W8×18 cut, formed, or fabricated? Huntington Steel & Supply Co.

Browse more: Wide flange beams · Steel Beam Size Chart

Interactive drawing