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Structural · W — wide-flange

W18x40 Steel Beam — Dimensions & Properties

W18x40 weighs 40 lb/ft and is about 17.9 in deep. Below: the full AISC section properties, a scaled cross-section, and a pre-filled weight calculator.

Weight
40lb/ft
Depth
17.9in
Width
6.015in
Area
11.8in²
Shape
W18X40 · 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 × W18X40
800lb
Per piece
800lb
Pieces
1
Total
800lb
Tons
0.4t
d17.9"bf 6.015"tw 0.315
ƒShow the math
  1. 1.Weight per foot (from AISC)per AISC Shapes Database v16.0

    W18X40 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
11.8in²
Depth, d
17.9in
Flange width, bf
6.015in
Flange thick, tf
0.525in
Web thick, tw
0.315in
Strong axis (x-x)
Ix
612in⁴
Sx
68.4in³
Zx
78.4in³
rx
7.21in
Weak axis (y-y)
Iy
19.1in⁴
Sy
6.35in³
Zy
9.95in³
ry
1.27in
Torsion & warping
J
0.81in⁴
Cw
1,440in⁶
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.

W18x35 35 lb/ftW18x46 46 lb/ftW18x50 50 lb/ftW18x55 55 lb/ftW18x65 65 lb/ftW18x76 76 lb/ftW18x86 86 lb/ftW18x97 97 lb/ftW16x100 100 lb/ftW16x89 89 lb/ft

W18x40 — questions

How much does a W18x40 weigh per foot?
A W18x40 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 W18x40?
W18x40 has an actual depth of 17.9 in and a flange width of 6.015 in, a flange thickness of 0.525 in, and a web thickness of 0.315 in. Cross-sectional area is 11.8 in².
What is the moment of inertia and section modulus of a W18x40?
About its strong axis, W18x40 has a moment of inertia Ix of 612 in⁴ and a section modulus Sx of 68.4 in³, with a plastic section modulus Zx of 78.4 in³. Use these with your engineer's design values — they are geometric properties, not an allowable load.
What does W18x40 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 W18x40 is a nominally 18-inch-deep wide-flange beam weighing 40 lb/ft (actual depth 17.9 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.