Retaining Wall Calculator
Estimate blocks, capstones and base gravel for a retaining wall.
Use this retaining wall calculator to estimate the blocks, capstones and base gravel needed for your project. It calculates blocks per course and the number of courses, then estimates the total number of blocks. It also allows for one row of capstones and 6 in of base gravel in a 12 in wide trench.
Wall blocks
120
6 courses
Capstones
20
1 per block length
Base gravel
0.37
yd³ · 6 in deep × 12 in wide
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Recommended tools & materials
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Brick Trowel
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Type S Mortar Mix
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Mason's Line & Line Blocks
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How does the retaining wall calculator work?
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.
What else do people ask about this calculator?
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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Where can I learn more about these materials?
Weights, coverage, types and buying tips for the materials this calculator estimates.
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