The block count on a retaining wall adds up quickly once you start stacking rows. Enter your wall length and height here to get totals for wall blocks, cap blocks, and base gravel before you place an order.
Wall Dimensions
ft
ft
Block Face Dimensions
in
in
Scenario: You're building a 25 ft long, 2.5 ft tall retaining wall with 12 x 4 inch face blocks.
Result: You need 25 blocks per row x 7.5 rows (round to 8) = 200 wall blocks, plus 25 cap blocks. Base gravel: about 0.46 cubic yards.
Divide wall length (in inches) by block width for blocks per row. Divide wall height (in inches) by block height for row count. Multiply those two numbers together and add 10% for cuts, more if the wall curves.
3-4 feet in most municipalities. Above 4 feet, you'll need an engineer, geogrid reinforcement, and a building permit. Check your local codes before you start.
Place 12 inches of gravel behind the wall from base to top, with a perforated drain pipe at the base angled to daylight. This prevents water pressure from pushing the wall forward. Use landscape fabric to keep soil out of the gravel.
Dig a trench 6 inches deep and 24 inches wide, then fill with compacted gravel. Bury the first course of blocks about halfway below grade. Skipping this step is the number one reason DIY retaining walls lean and fail within a few years.
Want to learn more before you start your project?
Read the full guide →
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