Retaining Wall Block Calculator

Divide the wall length by the block face length for one course, and the wall height by the block face height for the number of courses, rounding each up. Multiply the two for the wall blocks, then add one course of caps if used.

Because you cannot buy a fraction of a block. A 20 foot wall in 12 inch blocks is exactly 20 per course, but any wall length that does not divide evenly is rounded up so the last block fully covers the end of the row.

Use the face length and face height of your specific block, since brands vary. The default is a common 12 inch long by 8 inch high segmental unit, but a wider 18 inch block or a shorter 6 inch course will change both the per course count and the number of courses.

Only if you tick Add a cap course. When it is on, the tool adds one extra row equal to the blocks per course, since caps run along the top just like a normal course. The Cap blocks tile shows that number separately.

Many segmental walls taller than about 3 to 4 feet require engineering, geogrid reinforcement and a permit. Check local codes before building tall, and consider stepping or terracing a high slope into shorter walls.

Bury roughly one inch of wall for every foot of height so the bottom course sits below grade for stability. Add that hidden height to the Wall height field so the calculator counts the buried base blocks in your total.

No. It counts wall and cap blocks only. Budget separately for a compacted gravel leveling base, free-draining backfill stone behind the wall, and a perforated drain pipe at the bottom to relieve water pressure.

Yes. Add a few percent for breakage, cuts at corners or curves, and color matching across pallets. The tool gives the exact geometric count, so round your order up when you buy.

No. The estimate is calculated in your browser, so the dimensions you enter stay on your device and nothing is uploaded.