S20×66 standard 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.

S20×66 measures 20 in. deep with a 6 1/4 in. flange, on a 1/2 in. web and 13/16 in. flanges.

At 66 lb per foot it is the lightest of the 4 S20 sizes, which run from 66 to 96 lb/ft.

For strong-axis bending its section modulus is Sx = 119 in³ and its moment of inertia Ix = 1190 in⁴, with a plastic modulus Zx = 139 in³.

Detailing dimensions

Depth (d)20"
Flange width (bf)6 1/4"
Web thickness (tw)1/2"
Flange thickness (tf)13/16"
k (detailing)1 5/8"
Workable gage (g)3 1/2"

Section properties

Weight66 lb/ft
Area (A)19.4 in²
Ix1190 in⁴
Sx119 in³
Zx139 in³
rx7.83 in
Iy27.5 in⁴
Sy8.78 in³
Zy15.4 in³
ry1.19 in
J3.58 in⁴

Other S20 sizes

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

S20×75S20×86S20×96

Similar weight standard beams

Comparable 66 lb/ft sections in other standard beam sizes.

S18×7070 lb/ft · Sx 103 in³S18×54.754.7 lb/ft · Sx 89 in³S24×8080 lb/ft · Sx 175 in³S15×5050 lb/ft · Sx 64.7 in³S12×5050 lb/ft · Sx 50.6 in³S15×42.942.9 lb/ft · Sx 59.4 in³S24×9090 lb/ft · Sx 187 in³S12×40.840.8 lb/ft · Sx 45.1 in³

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 S20×66 cut, formed, or fabricated? Huntington Steel & Supply Co.

Browse more: Standard beams · Steel Beam Size Chart

Interactive drawing