Retaining Wall Calculator
Enter your wall length and height, pick a material, and get an instant estimate of blocks needed, gravel, drainage materials, and total cost.
Pre-filled with a 20 ft long, 3 ft high concrete block wall. Edit to match your project.
Material Type
Concrete Block: $10–$15/sq ft installed
Concrete Block Needed (incl. 10% waste)
75blocks
Wall Face Area
60 sq ft
Cap Stones
15
Gravel (total)
(base + backfill)
4.00 tons
Material Cost
$600–$900
Full Materials List — Concrete Block
| Material | Quantity | Notes |
|---|---|---|
| Concrete Blocks | 75 | Includes 10% waste |
| Cap Stones | 15 | Finished top course |
| Base Gravel (crushed stone) | 1.00 tons | 6" deep x 2 ft wide trench |
| Backfill Gravel | 3.00 tons | 1 ft deep behind wall |
| Perforated Drain Pipe | 20 ft | 4" pipe at base of wall |
| Filter Fabric (landscape) | 100 sq ft | Between soil and backfill |
Material Cost Comparison(60 sq ft wall)
Installed cost rule of thumb: Professional installation typically doubles or triples the material cost. A 60 sq ft retaining wall averages $1500–$3000 fully installed including excavation, drainage, and labor.
What Is a Retaining Wall Calculator?
A retaining wall calculator converts your wall dimensions and material choice into a complete shopping list: how many blocks or stones you need, the gravel for the base and backfill, drainage pipe, and filter fabric. It also estimates material and installed costs so you can compare options before heading to the supply yard.
Key formula: Wall Face Area (sq ft) ÷ Block Face Area × 1.10 = Blocks Needed
The 10% overage accounts for cuts, breakage, and irregular terrain.
How to Use This Calculator
- 1Measure your wall’s total length in feet. For curved walls, measure the centerline arc.
- 2Measure the exposed height from the finished grade to the top of the wall. Add 4–6 inches for the buried base course.
- 3Choose your material: concrete block is most affordable, natural stone is premium, and interlocking blocks are DIY-friendly.
- 4Review the full materials list including base gravel, backfill, drainage pipe, and filter fabric.
- 5Compare material costs side by side. Use Print or Copy to bring the estimate to your supplier.
How Much Does a Retaining Wall Cost?
Retaining wall costs vary dramatically by material and whether you DIY or hire a professional contractor. Here are typical price ranges per square foot of wall face:
| Material | Material/sq ft | Installed/sq ft |
|---|---|---|
| Concrete Block | $10–$15 | $25–$40 |
| Natural Stone | $20–$35 | $50–$85 |
| Timber / Railroad Tie | $15–$25 | $25–$50 |
| Interlocking Block | $12–$20 | $30–$50 |
Quick math: A 20 ft x 3 ft concrete block wall (60 sq ft) costs roughly $600–$900 in materials or $1,500–$2,400 installed.
Retaining Wall Planning Tips
Always install proper drainage
Water pressure behind a wall is the #1 cause of failure. Use perforated drain pipe at the base, backfill with gravel (not soil), and install filter fabric to prevent clogging.
Bury the first course
Set the bottom row 4–6 inches below grade on a compacted gravel base. This anchors the wall and prevents frost heave from pushing it forward.
Step the base on slopes
For walls on a slope, step the gravel base every 4–6 feet to follow the terrain. Each step should be one block height. This keeps every course level.
Need gravel for other projects? Our calculator handles driveways, patios, and drainage systems too. For full project budgeting, check the landscaping cost calculator.
Related Tools & Guides
Gravel Calculator
Calculate cubic yards and tons for driveways, paths, and base layers
Paver Calculator
Estimate pavers, sand, and base material for patios and walkways
How to Build a Retaining Wall
Step-by-step guide from excavation to cap stone placement
Landscape Drainage Solutions
French drains, grading, and water management for retaining walls
Landscaping Cost Calculator
Get a full budget estimate for your entire landscaping project