Handrail, Post & Balustrade Calculator
Estimate posts and handrail lineal metres for a deck balustrade. This is a materials guide only — it does not determine post spacing, height or sizing for your project.
Balustrade height and post spacing are safety-critical and set by the National Construction Code / Queensland Development Code, and vary by post size and timber grade.
Published guidance for timber newel/full-height posts ranges from about 1.3m up to 3.6m centres depending on grade and post size — there is no single "safe default." Confirm your exact spacing and height with a certified builder or your local council before ordering or building. This tool only calculates quantities for the numbers you enter.
Only count the open edges that need a balustrade — usually not the side against the house. Post height should be your confirmed, code-compliant height, not a guess.
Advanced options (waste allowance)
Estimated materials
| Approx. posts required | — |
| Total post lineal metres (incl. waste) | — |
| Total handrail lineal metres (incl. waste) | — |
Post count assumes one post at each end plus intermediate posts at your entered spacing. Browse our Merbau posts and handrail battens, or check the Span Tables page. Call our Archerfield team to confirm compliant spacing and sizing before you order.