Wood Beam Span Calculator

Inputs

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Common North American dressed lumber sizes. Use custom for actual measured width and depth.
On-center spacing. Area loads are multiplied by this tributary width to get line load.
in
Uniform live or snow/roof live load on the tributary area.
psf
Uniform dead load on the tributary area, including sheathing, finishes and member self-weight allowance.
psf
Use the adjusted modulus value required by your design basis. Default is an example only.
Mpsi
Adjusted allowable bending design value for the selected species/grade/size and conditions. Default is an example only.
ksi
Adjusted allowable shear design value. Default is an example only.
ksi
For L/360, enter 360. Applied to live-load deflection only.
For L/240, enter 240. Applied to live plus dead load deflection.
Optional span to check against the same bending, shear and deflection criteria.
ft

Results

Default result
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Allowable span(L_allow)
14.63ft
Pass

Governing allowable span check: bending stress.

Minimum of bending, shear, live-deflection and total-deflection spans.

Also computed

Checked-span utilization(U_max)Pass0.6732

Utilization at the entered check span (2x10 actual 1.5 x 9.25 in).

Bending-controlled span(L_b)14.63ft

Shear-controlled span(L_v)37.46ft

Live-deflection span(L_delta,L)14.88ft

Total-deflection span(L_delta,T)15.82ft

Total line load(w)66.67lb/ft

Surface live + dead load multiplied by member spacing.

Method notes 4 notes
  • Uses 2x10 actual 1.5 x 9.25 in; line load is area load multiplied by spacing.
  • Simple-span uniform-load screen only: M = w*L^2/8, V = w*L/2, delta = 5*w*L^4/(384*E*I).
  • Enter adjusted E, Fb and Fv values from the same code/design edition and product/species/grade basis. Defaults are examples, not a species table.
  • Does not check bearing, notches, holes, lateral restraint, vibration, repetitive-member factors, load duration, wet service, snow drift, seismic/wind uplift, connections or local code acceptance.

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