Retaining Wall Calculator
Use the retaining wall calculator to estimate both the amount of materials needed and the price of your project.
The method
blocks = wall area ÷ block face; base = length × width × depth
The wall you can see is the easy part
A retaining wall holds back soil that gets heavier every time it rains, and water pressure behind an undrained wall is what pushes most of them over. The gravel band behind the blocks and a pipe at the bottom are not optional extras.
Bury the first course — one full block, or about a tenth of the wall height, whichever is more — on a compacted gravel base roughly twice the block width. That base is what stops the wall settling unevenly.
Above about four feet the loads stop being something to estimate. Most jurisdictions require an engineered design at that point, and they are right to.