Retaining Wall Calculator

Divide the wall height by the block face height to estimate the number of rows, then divide the wall length by the block face length to estimate blocks per row. Multiply those two figures for a baseline block count, then add cap units and a waste allowance for cuts, steps, corners, or curves.

That depends on the wall system and drainage detail, but most retaining walls need free-draining aggregate behind the blocks to reduce water pressure. The calculator gives a simple planning quantity only; the final gravel layout should follow the chosen wall system.

Yes. Drainage aggregate behind the wall is standard practice because water pressure can build up quickly and push the wall out of alignment. Many systems also use drainpipe and other drainage details, which should be checked against the manufacturer guidance.

A straight wall usually needs cap units equal to the number of block positions across the top run, but corners, curves, and special cap shapes can change that total. The calculator gives a straight-wall baseline so you can start pricing the top course.

That depends on local code, wall height, the slope above or below the wall, and surcharge loads such as vehicles or fences. Many taller or load-bearing walls need engineered design or permit review even if the material estimate itself looks straightforward.