Steel Beam Size Calculator

The lightest AISC W-shape that carries a uniformly loaded simple span in flexure, shear and deflection, by LRFD or ASD, with the next heavier options that also work.

AISC 360-16

Basis

Span and loads

Limits

W14x22 · 22 lb/ft · governed by deflection

W14x2222 lb/ft · d = 13.7″ · Zx = 33.2 in³ · Ix = 199 in⁴Flexure0.74Shear0.16Deflection0.811.00
Section — W14x22
22
Depth
13.70 in
Live-load deflection
0.65 in
Total-load deflection
1.16 in

Heavier options that also work

Sometimes the lightest section is not the one you want — a shallower beam buys headroom, a deeper one buys stiffness.

Sectionlb/ftd (in)Worst DCR
W12x262612.20.79
W14x262613.90.66
W16x262615.70.56

Needs Zx ≥ 24.6 in³ and Ix ≥ 161 in⁴ · strength alone: W12x19 · stiffness alone: W14x22

Design checks

CheckDemandCapacityDCRStatus
Flexure92.160 kip·ft124.500 kip·ft0.740✓ OK
Shear15.360 kip94.530 kip0.162✓ OK
Live-load deflection (L/360)0.647 in0.800 in0.808✓ OK

Calculation

  1. 1Factored design loadASCE 7, document reference
    w_u = 1.2D + 1.6L
    w = 1.280
    w_u1.280 kip/ft
  2. 2Moment and shear on a simple span
    M = \frac{wL^2}{8}, \quad V = \frac{wL}{2}
    M = 92.2, \quad V = 15.4
    M_u92.2 kip·ft
  3. 3Plastic modulus requiredAISC360 F2.1
    Z_{x,req} = \frac{M_u}{\phi_b F_y}
    Z_{x,req} = 24.600 \text{ in}^3
    Z_{x,req}24.6

    φb = 0.9, Fy = 50 ksi.

  4. 4Second moment of area required for the deflection limit
    I_{x,req} = \frac{5 w_L L^4}{384 E \Delta_{allow}}, \quad \Delta_{allow} = \frac{L}{360}
    I_{x,req} = 161 \text{ in}^4 \quad (\Delta_{allow} = 0.80)
    I_{x,req}161

    Unfactored live load. Deflection is a serviceability question, so the load factors do not apply to it.

Notes

  • Deflection governs. The section is stronger than it needs to be, and stiffness is what set its size — a shallower, heavier shape will not help.
  • Strength alone would allow W12x19 at 19 lb/ft. The deflection limit is what pushed the selection to W14x22.

Assumptions

  • Simply supported, single span, uniformly loaded.
  • The compression flange is continuously braced, so the shape reaches its plastic moment.
  • The section is compact for flexure, which every rolled W-shape in this table is at the grades offered.
  • Deflection is checked on the unfactored live load against the stated limit, and the total load is reported alongside it.

What this calculator does not check

  • Selects a section. It does not design the connections, the bearing, the web at a point load, or any stiffener.
  • No lateral-torsional buckling. An unbraced or partially braced beam has a lower capacity than this reports, and is out of scope.
  • No check on web crippling or web yielding under a concentrated load or at a support.
  • No camber, vibration or floor-response check. A long-span floor beam that satisfies L/360 can still be unacceptably lively.
  • The shape table covers W8 to W30 up to 99 lb/ft only. A heavier or deeper section is not considered even if it would be the right answer.
  • Self-weight is reported but not added to the demands, matching the source tool. Include it in the dead load if it matters.

Results are for preliminary sizing and educational use. They are not a design and must be reviewed, verified and sealed by a licensed or registered engineer before being used in construction.

steel-beam-size v1.0.0 · AISC 360-16 · input 03d85de5e4bed328