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Structural · W — wide-flange

W8x40 Steel Beam — Dimensions & Properties

W8x40 weighs 40 lb/ft and is about 8.25 in deep. Below: the full AISC section properties, a scaled cross-section, and a pre-filled weight calculator.

Weight
40lb/ft
Depth
8.25in
Width
8.07in
Area
11.7in²
Shape
W8X40 · W — wide-flange

Enter feet + inches, e.g. 20' or 18' 6".

= 20' (240″)
pcs
Cost estimate (optional)
$/lb

Optional. Prices are volatile — use your current mill/supplier rate.

Total weight
1 × W8X40
800lb
Per piece
800lb
Pieces
1
Total
800lb
Tons
0.4t
d8.25"bf 8.07"tw 0.36
ƒShow the math
  1. 1.Weight per foot (from AISC)per AISC Shapes Database v16.0

    W8X40 is a listed shape; its nominal weight is a published property.

    = 40 lb/ft
  2. 2.Length in feet
    length (in) ÷ 12
    240 ÷ 12
    = 20 ft
  3. 3.Weight per piece
    weight per foot × length
    40 × 20
    = 800 lb
  4. 4.Total weight
    weight per piece × quantity
    800 × 1
    = 800 lb
  5. 5.Convert to tons
    total lb ÷ 2000
    800 ÷ 2000
    = 0.4 tons

Section properties

Geometry
Weight
40lb/ft
Area, A
11.7in²
Depth, d
8.25in
Flange width, bf
8.07in
Flange thick, tf
0.56in
Web thick, tw
0.36in
Strong axis (x-x)
Ix
146in⁴
Sx
35.5in³
Zx
39.8in³
rx
3.53in
Weak axis (y-y)
Iy
49.1in⁴
Sy
12.2in³
Zy
18.5in³
ry
2.04in
Torsion & warping
J
1.12in⁴
Cw
726in⁶
Before you rely on this
  • Listed weight is the AISC theoretical (nominal) weight per foot. Actual mill weight varies within ASTM rolling tolerance, roughly ±2.5%.
  • This is bare member steel only. Add plates, stiffeners, connections, bolts, and coatings for a full erected-steel takeoff.

Similar shapes

Same series and nearest depths — compare weight and section modulus when you are sizing.

W8x10 10 lb/ftW8x13 13 lb/ftW8x18 18 lb/ftW8x24 24 lb/ftW8x31 31 lb/ftW8x48 48 lb/ftW8x67 67 lb/ftW10x33 33 lb/ftW10x12 12 lb/ftW10x49 49 lb/ft

W8x40 — questions

How much does a W8x40 weigh per foot?
A W8x40 weighs 40 lb/ft. Over a 20-foot length that is 800 lb (0.4 tons); a 30-foot length is 1,200 lb.
What are the dimensions of a W8x40?
W8x40 has an actual depth of 8.25 in and a flange width of 8.07 in, a flange thickness of 0.56 in, and a web thickness of 0.36 in. Cross-sectional area is 11.7 in².
What is the moment of inertia and section modulus of a W8x40?
About its strong axis, W8x40 has a moment of inertia Ix of 146 in⁴ and a section modulus Sx of 35.5 in³, with a plastic section modulus Zx of 39.8 in³. Use these with your engineer's design values — they are geometric properties, not an allowable load.
What does W8x40 mean?
The W means wide-flange. The first number is the nominal depth in inches and the second is the weight in pounds per foot — so W8x40 is a nominally 8-inch-deep wide-flange beam weighing 40 lb/ft (actual depth 8.25 in).

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Sources & references

Estimates for planning purposes only. Verify all results against the code edition adopted in your jurisdiction and with your Authority Having Jurisdiction (AHJ). This tool is not a substitute for a licensed professional engineer. See our methodology, sources, and code editions.

Data: AISC Shapes Database v16.0, © AISC — used per its developer-use provision.