Beam Span Estimator
A rule-of-thumb span-to-depth guide for timber or reinforced concrete beams. Use as a starting point only — always verify with a structural engineer.
Measurements
How this is calculated
Minimum depth = span ÷ ratio, where the ratio depends on material and load:
- Timber: span ÷ 18 to 24 (heavy to light loads)
- Reinforced concrete: span ÷ 10 to 15 (heavy to light loads)
For timber, a common guide width is roughly half the depth — this is indicative only.
Real designs must account for point loads, continuous spans, deflection limits, and local building codes.
Related reading
Rule-of-thumb only — not a structural design. Beam sizing depends on load, support conditions, timber grade, steel reinforcement, and local codes. Always consult a qualified structural engineer before building.