A solid start for your next project
Retaining wall materials calculator
Estimate retaining-wall face units, posts, post-hole concrete and drainage aggregate from your specified wall-system dimensions and quantities.
Your result
Your plan starts
with a few details.
Enter your project measurements and product details, then calculate to see an estimated take-off.
How it works
Select a cited Adbri sleeper or AB Classic block to load its published face dimensions, or choose custom dimensions. Enter wall height, actual design quantities, post and drainage details as required.
The selected state or territory changes the sourced height warning. It is not an exemption decision: source-specific boundary, loading, planning, building and site conditions must still be checked. Geogrid area is specified layer count times wall length times embedment.
Formula
Wall units and posts
Courses = ceil(wall height ÷ unit face height) Units per course = ceil(wall length ÷ unit length) Posts = ceil(wall length ÷ specified spacing) + 1This estimates face coverage only. It does not size or select a retaining-wall system.
Concrete and drainage
Concrete per hole = (π × hole radius² − post width²) × hole depth Drain aggregate volume = wall length × entered zone width × entered zone depthConcrete bags are rounded up using your entered product yield. Aggregate tonnes use the entered density.
Worked example
For a 6 m wall with 0.2 m long and 0.2 m high units, face coverage gives 30 units per course. A 1.2 m wall takes 6 courses, or 180 units before the entered cutting allowance. At a specified post spacing of 1.5 m, the post count is ceil(6 ÷ 1.5) + 1 = 5. These are geometric examples, not structural recommendations.
Assumptions and limits
This tool is a material take-off, not a retaining-wall design. It does not check soil pressure, surcharge, drainage performance, foundations, connections, stability or the suitability of a wall system.
Australian approval rules vary by state, territory, site and boundary conditions. Victorian guidance states a permit is required for walls 1 m or more high and for walls on or near boundaries where adjoining-property damage is a risk. The NCC also notes that state and territory legislation may add requirements. This page does not decide whether a wall is exempt.
Frequently asked questions
Does this calculator tell me if a retaining wall is exempt from approval?
The result compares height with a cited state or territory warning reference and explains source-specific conditions. It does not declare the wall exempt; planning, building, boundaries, loading and local conditions need separate checks.
Does it choose the post spacing or geogrid?
No. Enter those dimensions only from the system manufacturer or a qualified wall design.
How is geogrid area measured?
The specified layer count is multiplied by wall length and embedment length. This is rectangular area in square metres. It does not select safe reinforcement spacing, embedment, laps or strength.
Does the counted wall height include a buried course?
Only the height you enter is counted. Include any buried face units required by the chosen wall system and design when preparing the take-off.
Sources
- Building and Plumbing Commission Victoria: landscapingChecked on
- NCC 2022 Housing Provisions, Part 3.1, ABCBChecked on
- NCC application in states and territories, ABCBChecked on
- Adbri Masonry concrete sleeper dimensions, June 2024 flyerChecked on
- Adbri AB Classic retaining-wall block dimensionsChecked on
- Shoalhaven City Council: NSW exempt retaining wallsChecked on
- Business Queensland: work not needing building approvalChecked on
- City of Wanneroo: retaining wallsChecked on
- Legal Services Commission of South Australia: retaining wallsChecked on
- Central Coast Council Tasmania: planning FAQsChecked on
- ACT Planning: check if you need building approvalChecked on
- NT Government: residential work requiring permitsChecked on
Specs as of: