Calculate the number of blocks, courses, and estimated cost for your retaining wall project.
Enter your wall's total length and height, then specify the face dimensions of the individual blocks you plan to use. The calculator instantly tells you how many blocks you need per course, how many courses high the wall will be, and the total block count — including a waste buffer for cuts and breakage. If you know the price per block, enter it to get a material cost estimate.
Toggle between Imperial (feet/inches) and Metric (meters/centimeters) depending on your project measurements. Results update every time you click Calculate.
Ordering too few blocks means a frustrating mid-project trip back to the supplier — and potentially no stock of the same batch, causing color mismatches. Ordering too many ties up cash and leaves you with pallets of material to return or store.
A typical 20-foot wide, 4-foot tall retaining wall using standard 12"×6" blocks requires around 160 blocks before waste — but with a 10% waste factor on a project that has corners, that jumps to 176 blocks. At $3.50 each, that's a $56 difference. For larger projects — say a 60-foot commercial wall at 6 feet high — the margin for error grows to hundreds of blocks and thousands of dollars.
This calculator is useful for homeowners building garden terraces, landscape contractors estimating bids, and DIYers tackling slope stabilization. It works for any interlocking concrete block system (Allan Block, Versa-Lok, generic CMU), natural stone cut to consistent sizes, and timber or railroad tie walls where the "block" size is a uniform timber section.
The math is straightforward and transparent:
All fractional blocks are rounded up because you cannot buy partial blocks — a wall that needs 4.2 blocks per row requires 5 blocks. The waste factor accounts for cut pieces at corners, damaged blocks during transport, and irregular ends.