Wood Beam Span Calculator

Inputs

Member size

Common North American dressed lumber sizes. Use custom for actual measured width and depth.

Member spacing (s)

On-center spacing. Area loads are multiplied by this tributary width to get line load.

Live area load (q_L)

Uniform live or snow/roof live load on the tributary area.

kPa

Dead area load (q_D)

Uniform dead load on the tributary area, including sheathing, finishes and member self-weight allowance.

kPa

Modulus of elasticity (E)

Use the adjusted modulus value required by your design basis. Default is an example only.

GPa

Bending design value (Fb)

Adjusted allowable bending design value for the selected species/grade/size and conditions. Default is an example only.

MPa

Shear design value (Fv)

Adjusted allowable shear design value. Default is an example only.

MPa

Live deflection limit (L/n)

For L/360, enter 360. Applied to live-load deflection only.

Total deflection limit (L/n)

For L/240, enter 240. Applied to live plus dead load deflection.

Span to check (L_check)

Optional span to check against the same bending, shear and deflection criteria.

Default result

Allowable span(L_allow)

4.458m

Pass

Governing allowable span check: bending stress.

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

Also computed

Checked-span utilization(U_max)0.6732

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

Bending-controlled span(L_b)4.458m

Shear-controlled span(L_v)11.42m

Live-deflection span(L_delta,L)4.537m

Total-deflection span(L_delta,T)4.821m

Total line load(w)0.9729kN/m

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.