Tools you might need next
Calculate mulch cubic yards or bags from bed area and depth. Estimate wood mulch, bark, and rubber mulch for landscaping beds and garden paths.
Calculate pavers needed for patio or walkway. Enter area, paver size, and pattern waste to get paver count, base gravel, and sand bedding quantities.
Calculate gravel cubic yards for driveways, paths, and drainage. Enter area and depth to get tons, cubic yards, and dump truck loads for crushed stone projects.
Wall face area = length × height. Divide by one block face area. Add 5% for cuts and caps.
Blocks = ceil(Wall Face Area ÷ Block Face Area × 1.05)Buried course plus 6″ compacted gravel base in trench width of 24″ minimum.
Base (cu yd) = Length × Trench Width × Depth ÷ 27Free-draining aggregate behind wall to daylight or drain pipe. Critical for hydrostatic pressure relief.
Drainage = Wall Height × Length × 12″ thick ÷ 27 cu ydUpdated: July 2026
120 sq ft face with 12×4×8″ blocks ≈ 540 blocks + cap units. No geogrid typically under 3 ft in stable soil.
4 ft height may need geogrid every 2 courses per manufacturer. Engineer required over 4 ft in many jurisdictions.
Curved wall uses more cut blocks — 10% waste. Compact base trench on undisturbed soil.
Plan segmental retaining wall materials before starting a garden or terrace project. Enter wall length, height, and block dimensions to get block count, gravel base, drainage aggregate, and geogrid layers for walls over 4 ft.