Steel Beam Sizes / AISC / W-Shapes / W8 / W8x31

W8x31 Steel Beam Dimensions and Properties

AISC Wide flange · v16.0

Analyze in Beam Calculator Back to W-Shapes All W8

Diagram, properties emphasis, and nearby alternatives use the selected unit system.

Units

Section diagram

W8x31 dimensions

Not to scale. Dimensions shown for reference.

Section properties

Symbols match the steel section finder. Imperial and metric values are shown side by side.

Property Imperial Metric
Weight 31.00 lb/ft 46.10 kg/m
Depth, d 8.00 in 203.00 mm
Flange width, bf 8.00 in 203.00 mm
tw 0.285 in 7.240 mm
tf 0.435 in 11.000 mm
Area 9.13 in² 5,890.00 mm²
Ix 110.00 in⁴ 45,800,000 mm⁴
Iy 37.10 in⁴ 15,400,000 mm⁴
Sx 27.50 in³ 451,000.00 mm³
Sy 9.27 in³ 152,000.00 mm³
Zx 30.40 in³ 498,000.00 mm³
Zy 14.10 in³ 231,000.00 mm³
rx 3.47 in 88.10 mm
ry 2.02 in 51.30 mm
J 0.54 in⁴ 223,000.00 mm⁴
Cw 530.00 in⁶ 142,000,000,000 mm⁶

Alternatives

Useful nearby sections

Same-series weight neighbors, closest Ix, and a nearby depth series when available — with percent change versus W8x31.

Browse W8 series →

Lighter in W8

W8x28

Weight
28.0 lb/ft (-9.7%)
Depth
8.06 in (+0.8%)
Ix
98.0 in⁴ (-11%)

Heavier in W8

W8x35

Weight
35.0 lb/ft (+13%)
Depth
8.12 in (+1.5%)
Ix
127.0 in⁴ (+15%)

Closest Iₓ in W8

W8x24

Weight
24.0 lb/ft (-23%)
Depth
7.93 in (-0.9%)
Ix
82.7 in⁴ (-25%)

Similar weight in W10

W10x30

Weight
30.0 lb/ft (-3.2%)
Depth
10.50 in (+31%)
Ix
170.0 in⁴ (+55%)
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Source: AISC Shapes Database v16.0 · Methodology