Understanding the Retaining Wall Calculator
A retaining wall calculator estimates the blocks, base material, and backfill needed to build a wall that holds back soil. Retaining walls do real structural work, so planning materials — and drainage — correctly is essential to a wall that lasts.
Blocks plus a proper base
The calculator estimates the number of wall blocks from the wall’s length and height, plus the gravel base course that the wall sits on. A solid, level, compacted base is the single most important factor in a retaining wall’s longevity — most failures trace back to a poor foundation.
Drainage and height limits
Water pressure behind a wall is a leading cause of failure, so gravel backfill and drainage are critical. Taller walls face dramatically greater soil pressure; many areas require engineering or permits above a certain height. For tall or load-bearing walls, consult a professional rather than relying on estimates alone.
Tips & things to know
- •A compacted, level gravel base is the key to longevity.
- •Include gravel backfill and drainage behind the wall.
- •Tall walls may require permits or an engineer.