Retaining Wall Block Calculator

Calculate blocks, base leveling sand, and drainage backfill gravel for your next wall project.

Total Blocks 60 Units (+10% Waste)
Base Sand 0.15 Estimated Tons
Drainage Gravel 3.25 Estimated Tons

Retaining Walls: More Than Just Blocks

A retaining wall's worst enemy is water. If you simply stack blocks and fill behind them with dirt, the weight of the wet soil will eventually push the wall over. Professional walls require three key components:

  • The Leveling Base: Your first course of blocks should sit in a trench on 1-2 inches of coarse **leveling sand** or crushed stone. This allows you to get the wall perfectly straight and prevents shifting.
  • Buried Course: For stability, at least half of the bottom block (or one full course for taller walls) should be buried below ground level. *This calculator includes one extra course in its block count to account for burial.*
  • Drainage Backfill: You should have roughly **12 inches of gravel** directly behind the blocks for the entire height of the wall. This allows water to drop straight down to a perforated drain pipe rather than pressing against the back of your blocks.