Retaining wall calculatorPro

How it's worked out

Blocks = wall face area × 12.5 per m² plus waste. Drainage gravel fills a 300 mm zone behind the wall. Base course is 600 mm wide and 150 mm deep. Walls higher than about 0.5–1 m usually need council approval and an engineer's design.

Estimates only. Check sizes, coverage and quantities with your supplier, engineer or certifier before ordering. Standards references are a guide, not compliance advice.