How to use it
- Enter the wall length and exposed height.
- Enter the block dimensions from the product sheet.
- Set how many courses will be buried.
The formula
Blocks per row = wall length ÷ block length
Rows = exposed height ÷ block height + buried rows
Base = length × (2 × block depth) × 6 in
Worked example
| Wall length | 30 ft |
| Wall height (exposed) | 3 ft |
| Block length | 12 in |
| Block height | 4 in |
| Block depth | 8 in |
| Buried courses | 1 |
| Waste / spillage allowance | 10 % |
Result
| Wall blocks | 330 blocks |
| Rows (incl. buried) | 10 |
| Blocks per row | 30 |
| Cap units | 30 |
| Base gravel (6 in) | 0.74 yd³ |
| Drainage gravel (12 in behind wall) | 3.7 yd³ |
Tips before you order
- Walls taller than about 3–4 ft usually need geogrid reinforcement and, in many places, an engineer's design.
- Backfill the first 12 in behind the wall with clean drainage stone and add a perforated drain pipe at the base.
Questions
How deep should a retaining wall base be?
Most block manufacturers specify a 6 in compacted gravel base and burying the first course.