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Retaining Wall Calculator
Estimate blocks, capstones and base gravel for a retaining wall.
How the retaining wall calculator works
Blocks per course = wall length ÷ block length. Courses = wall height ÷ block height. Total blocks = courses × blocks per course. Add one row of capstones and 6 in of base gravel in a 12 in wide trench.
Frequently asked questions
How many blocks for a 20 ft retaining wall?
A 20 ft × 2 ft wall using 12×4 in blocks needs 20 blocks per course × 6 courses = 120 blocks plus 20 capstones.
How deep should the base be for a retaining wall?
At least 6 in of compacted crushed stone in a level trench, plus bury the first course half-way for a wall up to 3 ft.
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