Retaining Wall Calculator
Estimate blocks, cap stones, base gravel, drainage stone, and cost for a segmental retaining wall. Enter wall dimensions and pick a block size.
⚠️Materials estimator only — not structural design. Walls over 4 ft need engineering review and permits.
How the retaining wall calculator works
- Courses = exposed height ÷ block height, rounded up. Add 1 buried course below grade for stability.
- Blocks per course = wall length × 12 ÷ block face length, rounded up.
- Total blocks = courses × blocks per course, plus waste factor for cuts.
- Cap blocks = one course on top, same count as blocks per course.
- Base gravel = 6" deep × (block depth + 6") wide × wall length, converted to tons at 1.45 tons/yd³.
- Drainage stone = 12" wide × exposed height × wall length, directly behind the wall.
Structural engineering note
This calculator estimates materials only. Walls over 4 feet tall, walls on slopes, or walls supporting heavy loads require engineering design — including geogrid reinforcement, drainage systems, soil bearing analysis, and local building permits. Always check with a qualified engineer and your local building department.