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Retaining Wall Block Calculator

Segmental retaining wall blocks stack in courses without mortar. Enter the wall length and height and the face size of your block to find the number of courses, blocks per course, total blocks and cap blocks.

Enter your measurements

Measurements
ft
ft

Walls over about 4 ft (1.2 m) often need engineering and a permit. Check local rules.

in
in
Material & assumptions

Many block manufacturers recommend burying the first course. Follow your product's installation guide.

%

Extra for cuts at corners, ends and broken blocks.

Enter your measurements and press Calculate to see quantities, a material breakdown and an optional cost estimate.

How the calculation works

  • Courses = Wall height ÷ Block height (rounded up) + Buried course
  • Blocks per course = Wall length ÷ Block length (rounded up)
  • Total blocks = Courses × Blocks per course × (1 + Waste %)

Rounding courses up means the built wall may be slightly taller than planned. If that matters, adjust the height or choose a block size that divides it evenly.

Assumptions used

  • Each course is a single row of blocks; stepped or terraced walls should be calculated section by section.
  • Drainage aggregate, base gravel and geogrid reinforcement are not included.

Example calculation

A 30 ft wall, 3 ft tall above grade, using 12 × 4 in blocks with one buried course and no waste.

  1. 1Visible courses: 36 in ÷ 4 = 9
  2. 2Total courses: 9 + 1 buried = 10
  3. 3Blocks per course: 30 ft ÷ 1 ft = 30
  4. 4Total: 10 × 30 = 300 blocks

Result: 300 blocks plus 30 cap blocks; add 5% or so for cuts.

How to measure your project

  • Measure wall length along the face. For curved walls, measure along the front face of the curve.
  • Measure height from finished grade at the front to the top of the wall.
  • Use the actual face dimensions listed on the product sheet.

Frequently asked questions

How tall can I build a retaining wall without an engineer?

Many jurisdictions require engineering or a permit for walls over about 3–4 ft (around 1 m), or for walls supporting driveways or buildings. Always check local regulations.

Why bury the first course?

Burying the first course helps resist sliding at the base. Manufacturers often recommend burying at least one course or a set fraction of the wall height.

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Results are estimates based on the measurements and assumptions you enter. Always confirm product specifications, local building codes and final quantities with your supplier or a qualified professional. See our disclaimer.