Retaining Wall Calculator

How Many Retaining Wall Blocks Do I Need?

For a straight wall with one block size, count blocks along each course and courses up the wall. Use the manufacturer's installed face width and course height. A rear lip, taper or decorative overhang may make the overall product dimensions different from its installed coverage.

This retaining wall block calculator rounds each direction before multiplying. An area-only estimate can miss the last partial block in every row. Cut pieces are counted as whole purchased units; the tool does not assume that an offcut from one row can be reused in another.

Example: a 20 ft straight wall

Suppose the exposed block face is 2 ft high and the plan specifies another 6 in below grade. With an 18 in working width and 6 in course height, the estimate is 14 blocks per course × 5 courses = 70 blocks. A chosen 5% extra allowance gives 73.5, rounded to 74 blocks. These dimensions illustrate the arithmetic; they are not a wall design.

The 8 in example rounds the block stack to 32 in, rather than trimming every block to reach 30 in. A quantity result may therefore exceed the requested height. Confirm the actual course layout before ordering.

Buried Courses and Caps: Count Them Separately

The part below ground still uses blocks. Enter the visible block height and the buried block height separately, using your project details. Do not add a second buried course if it is already included in a total height you measured.

Caps are a separate row with their own installed coverage. For a 20 ft top edge and caps covering 16 in each, 240 ÷ 16 gives 15 caps, before any cap-cut allowance. The cap row is added above the block height; it does not replace the highest block course in this model.

Stepped ground, stairs, corners, returns and mixed-size patterns require separate course schedules. A circle retaining wall calculator also needs the product's curve geometry: inner and outer edges have different lengths, and tapered units change the fit. Do not enter a diameter as the straight wall length or use this rectangular layout as a circular-wall takeoff.

What the Block Estimate Includes

The optional prices turn the selected block and cap counts into a material subtotal. If you are comparing a retaining wall cost calculator with a contractor quote, check which materials are included: base aggregate, drainage stone, reinforcement, drain outlets, adhesive, excavation and labor are outside this count.

Use the gravel calculator for a base or drainage zone whose dimensions have already been specified. This page does not choose those dimensions, select geogrid, or determine the wall's safe height.

For a concrete retaining wall calculator, first distinguish the construction: this tool counts precast segmental wall units. Poured concrete needs volume from a designed cross-section, while timber walls require a different component schedule. Ordinary hollow masonry blocks are not interchangeable with a selected retaining-wall system.