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.
What this is based on
Governed by AS 1684 span tables, or by an engineer for anything outside them. This calculator is deliberately scoped as a rule-of-thumb DEPTH ESTIMATE and must not be used to determine an actual permissible span. Span tables are a licensed compilation and are deliberately not encoded here.
We cite the clause and link to the publisher so you can read the source yourself. We do not reproduce the text or tables of the NCC or of any Australian Standard.