Estimate allowable beam span based on load, section modulus, moment of inertia, allowable bending stress, modulus of elasticity, and deflection limit. Use this beam span calculator for simple-span beams, floor beams, deck beams, roof beams, headers, girders, and preliminary structural planning.
Uniform load span:
The calculator estimates allowable span based on a uniformly distributed line load.
Center point load span:
The calculator estimates allowable span for a single concentrated load placed at midspan.
Bending check:
The calculator compares bending demand to allowable bending capacity using section modulus and allowable stress.
Deflection check:
The calculator estimates span based on stiffness using modulus of elasticity, moment of inertia, and the selected deflection limit.
A beam span calculator helps estimate whether a beam can reasonably span a given distance under a selected load.
It can help compare allowable span, bending-controlled span, deflection-controlled span, reaction load, total load, bending moment, and basic span status before final design.
Your result shows estimated allowable span, bending-controlled span, deflection-controlled span, entered span status, support reaction, bending moment, estimated deflection, and span ratio. These are planning estimates only and do not replace structural design.
Beam span is the clear distance between supports. Longer spans usually require stronger or deeper beams because bending and deflection increase as span increases.
Beam span can be controlled by bending strength, shear strength, deflection, vibration, bearing, connections, material grade, beam size, and local code requirements.
L/360 means the beam deflection limit equals span divided by 360. For a 12-foot span, L/360 allows about 0.4 inches of deflection.
No. This calculator gives a simplified estimate. Approved span tables, engineered design, product-specific tables, and local building codes should be used for final beam selection.