Retaining Wall Calculator — Blocks & Caps
Estimate retaining-wall courses, full blocks, caps, buried depth, allowance, and material cost from exact product dimensions.
A basic retaining-wall block count divides wall length by block face width and total wall height—including the entered buried depth—by block face height. Courses and blocks are rounded up before allowance and cap quantities are added.
6 courses × 27 blocks per course before allowance · 29 caps.
- Retaining-wall block171 blocks
- Wall caps29 caps
This tool estimates rectangular units only. Corners, curves, step-ups, stairs, partial units, pattern mixes, buried courses, and product-specific setbacks can change the count.
Retaining walls can fail dangerously. An approved design must address soil, drainage, base, embedment, surcharge, height, geogrid, global stability, utilities, permits, and the selected system's instructions.
Use the exact block and cap dimensions from the local product specification and ask the supplier about pallet quantities and return rules.
Step by step
- 1
Use the exact face dimensions for the selected wall block and include the buried course or embedment shown on the approved design.
- 2
Calculate straight rectangular sections first, then add product-specific quantities for corners, curves, step-ups, stairs, and partial units.
- 3
Do not build from a block count alone: verify soil, drainage, base, surcharge, geogrid, stability, utilities, permits, and the complete engineered or manufacturer-approved system.
Check the estimate before you buy
Estimate modular retaining-wall courses, blocks, caps, buried depth, allowance, and cost using exact product face dimensions.
A 40 ft wall with 3 ft exposed height plus 6 in buried depth uses six 8-in courses. With 18-in-wide blocks, each course needs 27 blocks, or 162 before allowance; 5% raises the order to 171 blocks plus about 28 caps.
How the calculation works
Wall length is divided by block face width and rounded up per course. Exposed plus buried height is divided by block face height and rounded up to full courses. Those counts are multiplied before allowance; caps are calculated separately.
Retaining Wall Calculator — Blocks & Caps FAQ
Should I buy exactly the calculated amount of retaining-wall blocks?
Usually no. Cuts, spillage, breakage, uneven surfaces, batch matching, and package rounding can increase the order. Use the editable allowance and confirm the product label.
Why does the result round up?
Stores sell full bags, boxes, cans, rolls, panels, or pieces. The tool keeps the mathematical amount visible, then rounds the purchasing quantity up separately.
Does the calculator include buried blocks?
Yes, it adds the entered buried depth to exposed wall height when counting courses. The required embedment must come from the approved system or design.
Does this calculate gravel or geogrid?
No. Base, drainage aggregate, consolidation zone, drain pipe, geogrid, and soil quantities depend on the selected system and site-specific design.
Reference: Allan Block retaining-wall material estimation worksheet. Results are practical estimates; complete labels, package directions, product specifications, and qualified professional advice take priority.