Design smarter retaining walls with precise block counts. Compare costs, caps, and waste allowances in seconds. Use inputs for instant, jobsite-ready breakdowns every time.
Tip: Keep all measurements in the same unit system. Use ft for feet or m for meters.
| Wall length | Wall height | Block L×H×D | Waste | Buried course | Estimated wall blocks | Estimated cap blocks |
|---|---|---|---|---|---|---|
| 30 ft | 3 ft | 1×0.5×1 ft | 5% | Yes | 202 | 32 |
| 18 ft | 2.5 ft | 1×0.5×1 ft | 7% | No | 96 | 20 |
| 12 m | 1.2 m | 0.4×0.2×0.3 m | 5% | Yes | 216 | 32 |
Start with wall length and exposed height, then add any end-return length for corners. The calculator converts these values into an effective run so you do not under-order blocks when the wall turns back or wraps a patio edge. Record the unit system you will purchase in, because mixing feet and meters can distort counts. For stepped grades, measure each tier and run the calculator per tier, then combine totals.
Retaining wall units are sold by nominal length and height, but actual dimensions vary by manufacturer. Use the block length and height fields to match your product. The tool counts blocks per course and courses needed, rounding up for full units.
Most segmental walls begin with one course buried below grade to improve resistance to sliding and to lock the first row. Enabling the buried course option adds a full extra course to the quantity calculation, keeping your estimate realistic.
Cuts for curves, steps, and damaged units are common on site. A waste percentage increases both wall blocks and cap units using a single factor. For straight runs, 3–5% is typical; for tight curves or complex steps, 7–10% is safer.
Cap units protect the top course and provide a clean finish. If caps differ from wall blocks, enter the cap length so the calculator can compute the cap count independently. Waste is applied to caps as well for consistent ordering.
A compacted gravel base supports the wall and helps level the first course. Base volume is estimated from wall length, base width, and base thickness. Base width equals block depth plus an extra width allowance so the base extends beyond the face. Many crews target 4–6 inches (0.10–0.15 m) of compacted base, adjusted for soil conditions and frost depth daily.
Granular backfill behind the wall improves drainage and reduces hydrostatic pressure. The calculator estimates backfill volume using wall length, wall height, and a user-defined backfill depth. Pair this with drain pipe and outlet details from your design.
If you enter unit prices for blocks, caps, and gravel, the calculator produces an itemized cost estimate and total. Use this to compare suppliers, validate delivery quantities, and create a purchasing checklist that aligns with your schedule and crew capacity.
Counts are planning-grade and rounded up to full units. Accuracy improves when your block dimensions match the product and you include returns, buried course, and realistic waste for cuts and breakage.
Many segmental walls start with one course below grade for stability and leveling. Local soil, drainage, and design height matter, so confirm requirements with project drawings or a qualified installer.
Use 3–5% for straight walls with minimal cuts. Use 7–10% for curves, steps, or lots of terminations. Increase further if matching colors or blending lots is important.
Cap units often differ from wall blocks. Entering cap length lets the tool estimate caps correctly across the wall run, while still applying the same waste factor for consistent ordering.
Base volume equals wall length times base width times base thickness. Base width is block depth plus an extra allowance so the compacted base extends beyond the face and supports the first course.
No. It estimates the drainage/backfill zone behind the wall using your backfill depth. If you plan to reuse native soil beyond the drainage aggregate, estimate that separately based on your excavation shape.
Avoid mixing units. Convert all dimensions to one system before calculating. Consistent units prevent major rounding errors in courses and blocks per course.
Accurate quantities help you build safer walls, confidently today.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.