Steel Beam Sizes / AISC / S-Shapes / S12x31.8

S12x31.8 Steel Beam Dimensions and Properties

AISC American standard beams · v16.0

Analyze in Beam Calculator Back to S-Shapes

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

Units

Section diagram

S12x31.8 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 31.80 lb/ft 47.30 kg/m
Depth, d 12.00 in 305.00 mm
Flange width, bf 5.00 in 127.00 mm
tw 0.350 in 8.890 mm
tf 0.544 in 13.800 mm
Area 9.31 in² 6,010.00 mm²
Ix 217.00 in⁴ 90,300,000 mm⁴
Iy 9.33 in⁴ 3,880,000 mm⁴
Sx 36.20 in³ 593,000.00 mm³
Sy 3.73 in³ 61,100.00 mm³
Zx 41.80 in³ 685,000.00 mm³
Zy 6.44 in³ 106,000.00 mm³
rx 4.83 in 123.00 mm
ry 1.00 in 25.40 mm
J 0.88 in⁴ 365,000.00 mm⁴
Cw 306.00 in⁶ 82,200,000,000 mm⁶

Alternatives

Useful nearby sections

Same-series weight neighbors, closest Ix, and a nearby depth series when available — with percent change versus S12x31.8.

Heavier in S12

S12x35

Weight
35.0 lb/ft (+10%)
Depth
12.00 in (0.0%)
Ix
228.0 in⁴ (+5.1%)

Closest Iₓ in S12

S12x40.8

Weight
40.8 lb/ft (+28%)
Depth
12.00 in (0.0%)
Ix
270.0 in⁴ (+24%)

Similar weight in S10

S10x35

Weight
35.0 lb/ft (+10%)
Depth
10.00 in (-17%)
Ix
147.0 in⁴ (-32%)
Analyze in Beam Calculator Compare in S-Shapes finder

Source: AISC Shapes Database v16.0 · Methodology