Beam Load Calculator
Determine the support reactions, total loads, and bending moments acting on a simply supported beam. Enter your beam span, tributary width, and design loads to get both service-level and factored (LRFD) load values for structural analysis.
Distance between beam supports
Width of floor/roof area that loads the beam
Permanent structural weight per square foot
Occupancy/use load per square foot (IRC/IBC minimums)
Load per Foot = Total Load / Span
Support Reaction = Total Load / 2 (each end)
Max Moment = wL²/8 (UDL, simple span)
Max Shear = wL/2
Factored Load = 1.2D + 1.6L (per ASCE 7)
Factor Moment = (1.2D + 1.6L) × b × L²/8
Total = 10 + 40 = 50 psf
Load/foot = 50 × 10 = 500 plf
Total load = 500 × 16 = 8,000 lbs
Reaction each end = 4,000 lbs
Max moment = 500 × 16² / 8 = 16,000 ft-lbs
Shear = 500 × 16 / 2 = 4,000 lbs
Factored: 1.2×10 + 1.6×40 = 76 psf
Factored total = 76 × 10 × 16 = 12,160 lbs
Factored moment = 760 × 16²/8 = 24,320 ft-lbs
How do I calculate the total load on a beam?
Total load on a beam = Tributary Width × Span Length × Load per Square Foot. The tributary width is the floor/roof area that transfers load to the beam. For a center beam supporting both sides, tributary width equals the sum of half the distance to each adjacent support. Total Load (lbs) = Tributary Width (ft) × Span (ft) × Load (psf). Then divide by span to get load per linear foot: w = Total Load / Span.
What is the difference between dead load and live load for beams?
Dead load is the permanent weight of the structure itself - beams, joists, flooring, ceiling, fixtures, and built-in equipment. Typically 10-15 psf for residential floors. Live load is the temporary weight from occupants, furniture, movable equipment, snow, and storage. Building codes specify minimum live loads: 40 psf for residential floors (bedrooms 30 psf), 50-100 psf for commercial, 20-40 psf for roofs (plus snow). Total design load = 1.2 × Dead + 1.6 × Live (per ASCE 7 load combinations).
How do support reactions work for a simply supported beam?
For a simply supported beam with a uniformly distributed load, the support reactions are equal at both ends: R₁ = R₂ = Total Load / 2. For a point load at any position, reactions are: R₁ = P × b / L and R₂ = P × a / L, where a and b are distances from the load to each support. The sum of reactions always equals the total applied load. Reactions are critical for designing the bearing plates, columns, and foundations that support the beam.
What typical loads should I use for different building types?
Typical design loads per building code (ASCE 7 / IBC):<br>Residential bedrooms: 30 psf live + 10 psf dead = 40 psf total<br>Residential living areas: 40 psf live + 10 psf dead = 50 psf total<br>Office areas: 50 psf live + 15 psf dead = 65 psf total<br>Retail stores: 75 psf live + 15 psf dead = 90 psf total<br>Roof (no snow): 20 psf live + 10 psf dead = 30 psf total<br>Roof (with snow): 40-70 psf snow + 10 psf dead = 50-80 psf total<br>Always verify with local building codes - these are minimums.
🔗 Related Calculators
📐 Formula
Load per Foot = Total Load / Span
Support Reaction = Total Load / 2 (each end)
Max Moment = wL²/8 (UDL, simple span)
Max Shear = wL/2
Factored Load = 1.2D + 1.6L (per ASCE 7)
Factor Moment = (1.2D + 1.6L) × b × L²/8
📝 Example Calculation
Total = 10 + 40 = 50 psf
Load/foot = 50 × 10 = 500 plf
Total load = 500 × 16 = 8,000 lbs
Reaction each end = 4,000 lbs
Max moment = 500 × 16² / 8 = 16,000 ft-lbs
Shear = 500 × 16 / 2 = 4,000 lbs
Factored: 1.2×10 + 1.6×40 = 76 psf
Factored total = 76 × 10 × 16 = 12,160 lbs
Factored moment = 760 × 16²/8 = 24,320 ft-lbs