Retaining Wall Calculator - Calculate Blocks Needed
Calculate retaining wall blocks and materials. Free calculator for wall height, length, and drainage.
Retaining Wall Calculator: Calculate blocks for retaining walls.
Materials Required
Wall Blocks
90
Cap Blocks
20
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Retaining Wall Materials
Calculate blocks by wall dimensions. Standard block: 12 (wide × 8) (tall × 12) deep. Blocks per sq ft: 1.5. Add cap blocks for top course. Include gravel backfill and drainage.
Frequently Asked Questions
How many blocks for retaining wall?
Calculate wall face area (length × height). Multiply by 1.5 blocks per sq ft. Add cap blocks (length / 1 ft). Example: 20 ft × 3 ft wall = 60 sq ft × 1.5 = 90 blocks + 20 caps.
How tall can retaining wall be?
DIY walls: up to 3-4 ft without engineering. Taller walls need professional design, geogrid reinforcement, and permits. Check local codes.
Do I need drainage behind retaining wall?
Yes, 4-6 inches gravel backfill with perforated drain pipe at base. Prevents water pressure buildup that causes wall failure. Essential for all retaining walls.
How much does retaining wall cost?
Block walls: $15-40 per sq ft installed. Natural stone: $25-75 per sq ft. Poured concrete: $20-50 per sq ft. DIY saves 40-60% on labor.
What is base for retaining wall?
6-8 inches compacted gravel base below frost line. Level and compact thoroughly. First course partially buried. Proper base prevents settling and failure.
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