Retaining Wall Block Calculator

Retaining Wall Block Calculator

Planning a retaining wall block order? This calculator converts your wall dimensions and chosen block size into a total block count.

Formula

Blocks Per Row = ceil(Wall Length / Block Width)
Number of Rows = ceil(Wall Height / Block Height)
Total Blocks = Blocks Per Row x Number of Rows

Example

A 20 ft long, 3 ft high wall using 18" x 6" blocks:

14 blocks per row x 6 rows = 84 blocks

What This Estimate Doesn't Include

This assumes a straightforward running-bond stack (blocks offset from the row below for structural stability) without accounting for corner blocks, curved sections, or a base course sometimes buried below grade for stability - actual material orders should add a modest buffer for these details plus normal breakage during handling.

When to Get Engineered Design

Taller retaining walls - typically anything over 3-4 feet - often require engineered design, geogrid soil reinforcement, and building permits, since the soil pressure behind a wall increases dramatically (not linearly) with height. Always check your local building code requirements before building a retaining wall beyond a modest garden wall height.