Retaining Wall Calculator
Plan a block retaining wall. Enter the wall length and height plus your block size to get the number of blocks, how many courses tall it will be, and an estimated material cost.
Your project
Estimate
Blocks needed · Includes waste allowance
- Wall face area
- 60ft²
- Courses (rows) tall
- 5courses
- Estimated material cost
- $380.00
Estimates are guidance only and exclude tax, labor, and site conditions unless stated. Confirm with a local pro.
How it's calculated
No black boxes — here is the exact math behind your estimate, so you can check it or adapt it for your own quote.
- 1
Wall face area (ft²) = length × height - 2
Block face area (ft²) = (block width ÷ 12) × (block height ÷ 12) - 3
Blocks = ⌈ (wall area ÷ block face area) × (1 + waste% ÷ 100) ⌉ - 4
Courses = ⌈ (height × 12) ÷ block height ⌉ - 5
Cost = blocks × price per block
Worked example
A 20 ft long, 3 ft tall wall using 12" × 8" blocks with 5% waste.
Inputs
- Wall length
- 20 ft
- Wall height
- 3 ft
- Block face width
- 12 in
- Block face height
- 8 in
- Waste allowance
- 5 %
- Price per block
- 4 $/block
Result
- Blocks needed
- 95 blocks
- Wall face area
- 60 ft²
- Courses (rows) tall
- 5 courses
- Estimated material cost
- $380.00
Tools & materials for this project
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- Masonry construction adhesive Bonds the cap and upper courses in place.
- Landscape fabric Separates backfill gravel from soil behind the wall.
Compare local pros for a retaining wall
An estimate gets you a budget. A few competing quotes get you the real price. Tell us about the job and we'll help you find vetted contractors nearby.
Retaining Wall cost by state
The calculator does the quantity math exactly. What it can't know is what a fair unit price looks like where you live — a retaining wall runs 61% more in the priciest US market than the cheapest.
Retaining Wall cost in all 50 states + DC US average $30 per square foot installed · regional averages, full ranked table, and typical project totals.