Retaining Wall Calculator
Calculate blocks, gravel, drainage, and cost estimates for your retaining wall.
Wall Type
Wall Dimensions
Your Results
Enter your wall dimensions above to see results
Common Wall Sizes – Segmental Block
| Size | Blocks | Cost Range |
|---|---|---|
| 10×2 ft | 60 | $300 – $600 |
| 20×3 ft | 180 | $900 – $1,800 |
| 30×3 ft | 270 | $1,350 – $2,700 |
| 40×4 ft | 480 | $2,400 – $4,800 |
| 50×4 ft | 600 | $3,000 – $6,000 |
*Illustrative segmental block coverage only; not a structural design.
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- Segmental block: A modular system whose actual unit size and installation specification determine quantities.
- Natural stone: Stone sizes vary; the displayed count is a rough allowance rather than a supplier order.
- Timber or concrete: These options have different structural details, durability considerations, and installation needs.
- Drainage and design: Height alone does not establish whether a wall is safe. Soil, slope, surcharge loads, groundwater, and local requirements all matter.
Frequently Asked Questions
How many retaining wall blocks do I need?
Multiply the wall face area by the assumed units per square foot. This calculator uses 3 for segmental block, 2 for stone, and 0.4 for timber; verify the actual product dimensions.
How high can I build a retaining wall?
There is no universal safe height. Consult local requirements and a qualified professional about site conditions, loads, and the chosen wall system.
Do I need drainage behind the wall?
Water management is an important part of wall design. The displayed gravel and pipe quantities are allowances, not an engineered drainage plan.
How much does a retaining wall cost?
The range is based on face area and the selected material. It is an illustrative budget, excluding any guarantee about excavation, engineering, foundations, and site access.
Should I order extra blocks?
The bonus section shows a 10% allowance for block, stone, and timber. Check cuts, buried courses, caps, corner units, and supplier pack sizes separately.