Retaining Wall Block Calculator (Materials Estimate)
How much to order for a modular block retaining wall: blocks and caps, drainage stone and leveling-pad gravel in cubic yards and tons, geogrid rolls, perforated drain pipe, filter fabric and excavation — with an optional cost total. Enter your block's face length, height and depth from the product sheet.
Blocks and caps round up per course and include the waste allowance; stone and fabric do not, so add your own margin. Geogrid is cut into pieces the design length long and laid side by side, perpendicular to the wall; offcuts shorter than one piece are not reused. Tons use the density you enter; crushed stone is commonly about 1.4–1.5 tons/yd³ but varies by rock and gradation. Corners, curves, steps in the base and stairs change the counts — add them by hand.
Worked example
Example — 40-ft garden wall, 3 ft exposed (the calculator defaults)
What people forget to order
- The buried course. At least one course below grade, more on slopes or soft ground.
- Clean crushed stone, not soil, behind the blocks. Most failed garden walls failed from water pressure, not weak blocks.
- An outlet for the drain pipe. A perforated pipe with nowhere to drain only stores water.
- Cap adhesive — coverage per tube is on the product label.
- Geogrid layers and length come from the design, not the estimate — see the geogrid wall calculator.
Related tools
- Segmental block retaining wall — will it stand without geogrid?
- Geogrid retaining wall — layers, strength, length
- Cantilever concrete retaining wall
- Soil nail wall
- Retaining wall design criteria (reference card)