Our Wood Beam Span Calculator helps you determine the safe span length, load capacity, and required dimensions for timber beams in construction. Prevent structural failure and ensure compliance by accurately assessing deflection and strength for floor joists, rafters, and headers. Input wood type, size, and load to get instant results.
Formula:
The safe span of a wood beam is determined by two primary factors: bending stress and deflection. The calculator finds the minimum span allowed by these two criteria.
- Bending Stress (Fb): The maximum stress a beam can withstand before breaking or failing due to bending.
- Modulus of Elasticity (E): A measure of the wood's stiffness, indicating its resistance to elastic deformation.
- Section Modulus (S): A geometric property of the beam's cross-section, indicating its resistance to bending. For a rectangular beam, S = (Width × Depth2) / 6.
- Moment of Inertia (I): A geometric property of the beam's cross-section, indicating its resistance to deflection. For a rectangular beam, I = (Width × Depth3) / 12.
- Distributed Load (w): The total load applied uniformly along the beam's length (Live Load + Dead Load).
- Deflection Limit (L/X): The maximum allowable vertical displacement relative to the span, typically L/360 for floors, L/240 for roofs.