Beam Load Calculator
Determines load capacity, deflection, and stress on structural beams by span and load
Total length of the beam between supports
Uniformly distributed load along the beam
Width of the beam cross-section
Depth (height) of the beam cross-section
Total distributed load on the beam (span x load/ft)
Maximum bending moment at midspan (wL²/8)
Geometric property of the beam cross-section (bd²/6)
Peak stress in the beam (moment x 12 / section modulus)
Frequently Asked Questions
What is bending stress in a beam?
Bending stress is the internal stress in a beam caused by external loads. It is highest at the top and bottom surfaces (tension on one side, compression on the other) and zero at the center (neutral axis). The formula is stress = M*c/I, where M is moment, c is distance from neutral axis, and I is moment of inertia.
What is section modulus?
Section modulus (S) is a geometric property that measures a beam's resistance to bending. For a rectangular beam, S = width x depth squared / 6. A deeper beam has a much higher section modulus than a wider one, which is why beams are oriented with the longest dimension vertical.
How do I determine if a beam is strong enough?
Calculate the maximum bending stress and compare it to the material's allowable stress. For structural lumber, allowable stress ranges from 600-2,400 psi depending on grade and species. For steel, it is typically 21,600-30,000 psi. The calculated stress must be less than the allowable stress with a safety factor.
Related Calculators
Crushed Stone Calculator
Estimates tons and cubic yards of crushed stone or gravel needed for a base or fill project
Excavation Volume Calculator
Calculates cut and fill volumes for excavation and grading projects
Snow Load Calculator
Calculates the weight of snow accumulation on a roof to assess structural risk
Demolition Debris Calculator
Estimates dumpster size and waste volume for demolition and renovation projects