Structural Load Calculator

How It Works

Wood beam load capacity depends on species strength (modulus of elasticity and bending stress), cross-section dimensions, and span length. Actual lumber dimensions are smaller than nominal: a "2x6" is actually 1.5" × 5.5". Load capacity decreases with the square of span length — doubling span cuts capacity by 75%. The L/360 deflection rule limits visible sag: a 10-foot span should deflect no more than 1/3 inch. Always apply safety factors: 2x for shelves, 2.5-3x for floors, and 3x or more for structural beams. When in doubt, consult a structural engineer for load-bearing applications.