Beam Span Calculator

Rule-of-thumb beam depth estimate for AU residential timber beams from span.

Estimate only — not a substitute for a licensed tradesperson, a certified engineer, or sign-off from your local building surveyor. Verify against current standards and site conditions before ordering materials or starting work.

Result

Indicative minimum beam depth: 180mm

This uses the common span/20 rule-of-thumb only, not the full AS 1684.2 span table (grade, load width, and tributary load all change the correct answer). Confirm against AS 1684.2 or a structural engineer before ordering timber.