Estimate the blocks and courses for a retaining wall from its length, height and block size — with a reminder to check engineering and permit requirements.
This is blocks only — you’ll also need base/road base, drainage aggregate, geofabric and an ag-line behind the wall. Check permit requirements for your height and location.
traqR keeps retaining wall quantities, plant and materials on the job card so nothing is left off the quote.
Start free trialLength times height gives the area of the wall face to be built from blocks.
One divided by a block’s face area (length × height in metres) gives how many blocks cover a square metre of wall.
Add a few percent for cuts, then divide the height by the block height for the number of courses and the length by the block length for blocks per course.
Work out the wall face area (length × height), divide by the face area of one block to get blocks per m², then add waste. A 10 m × 0.8 m wall in 295 × 200 mm blocks is 8 m² at about 17 blocks/m², so roughly 140 blocks with 5% waste.
Often, yes. Retaining walls above a certain height — commonly around 1 m, but it varies by council — and walls that support a load (a driveway, structure or slope above) generally require engineering design and a building permit. Always check your local requirements before building.
A proper retaining wall needs a compacted base, drainage aggregate behind the wall, geofabric, an ag-line (perforated drain) to relieve water pressure, and backfill. Water building up behind a wall is a common cause of failure, so drainage is not optional.
No — it only estimates block quantities. The wall’s footing, reinforcement, drainage and structural adequacy must be designed for the height, soil and loads, by a competent person or engineer where required.
This calculator estimates block quantities for a retaining wall face only. It does not design the wall or account for footings, drainage, reinforcement, surcharge loads or soil conditions. Retaining walls — especially over ~1 m or carrying loads — typically require engineering design and council approval. Seek professional advice.
traqR keeps retaining wall quantities, plant and materials on the job card so the full job is captured. Try it free for 14 days.