Wall and Cap Blocks
Calculates block courses, blocks per course, total wall units and cap blocks using your actual block face dimensions.
Retaining Wall Calculator
Estimate retaining wall blocks, cap blocks, gravel, drainage stone, landscape fabric, backfill and total material cost for your wall project.
Instant estimates
Block quantities
Cost planning
Project Measurements
Enter your wall and material specifications.
Please enter valid project measurements.
Material Estimate
Quantities include your selected waste allowance.
Estimated wall blocks
218
Standard retaining wall units including waste
Wall face area
120.00
ft²
Block courses
9
courses
Blocks per course
23
blocks
Cap blocks
25
caps
Complete material list
Estimate
Wall blocks
218 blocks
Cap blocks
25 caps
Compacted base gravel
1.28 yd³
Drainage stone
5.32 yd³
Landscape fabric
162.00 ft²
Wall block volume
1.10 yd³
Estimated material cost
$1,435.35
Based on the material prices entered above. Labor, delivery, permits and equipment are not included.
Retaining walls may require drainage,
reinforcement, permits or engineering. Consult
local building authorities and a qualified
professional for tall or load-bearing walls.
Project planning
What This Calculator Estimates
Plan the primary materials required for a segmental retaining wall before ordering supplies.
Base Gravel
Estimates compacted gravel needed beneath the wall using the selected trench width, base depth and compaction allowance.
Drainage Stone
Estimates the volume of clean drainage aggregate placed behind the wall to improve water movement.
Landscape Fabric
Provides an approximate fabric area for separating drainage stone from surrounding soil.
Waste Allowance
Adds an adjustable percentage for damaged blocks, cutting, corner pieces and project changes.
Material Cost
Creates a preliminary material budget using your local block, cap, gravel, stone and fabric prices.
Three simple steps
How to Use the Retaining Wall Calculator
Use accurate measurements and the manufacturer’s block dimensions to produce a practical project estimate.
Measure the Wall
Measure the total wall length and exposed height. Add the depth of the buried first course for a more realistic block estimate.
Enter Material Sizes
Enter the visible length and height of one block, cap length, gravel base dimensions and drainage stone width.
Review the Estimate
Review block quantities, gravel volumes, fabric area and estimated material cost before contacting suppliers.
How Retaining Wall Materials Are Calculated
A retaining wall material estimate begins with the wall face area. This is calculated by multiplying the wall length by its exposed height. The buried portion of the first course is then added when calculating the number of block courses.
The calculator uses the actual face dimensions of your selected retaining wall block. This is more accurate than relying on a general number of blocks per square foot because block dimensions vary between manufacturers.
Choosing a Waste Allowance
A waste allowance covers damaged units, cuts, curves, corners and measurement differences. A simple straight wall may need approximately 5 to 10 percent extra material. Walls with curves, steps or several corners may require a larger allowance.
Base Gravel and Drainage Stone
The gravel base supports the first block course and helps keep the wall level. Drainage stone is installed behind the wall to reduce water pressure and improve drainage.
- Use compactable crushed aggregate for the wall base.
- Use clean, angular drainage stone behind the wall.
- Compact the base in thin layers according to the project specifications.
- Provide a suitable drainage outlet when required.
- Follow the block manufacturer’s installation guide.
When Engineering May Be Required
Wall height is not the only factor that affects design. Slope, soil type, groundwater, nearby structures, vehicle loads and property boundaries can all increase pressure on a retaining wall.
Local regulations may require permits, geogrid reinforcement or engineering for certain projects. Always verify the requirements in your area before construction.
Common questions
Retaining Wall Calculator FAQs
Helpful answers for planning blocks, gravel, drainage and retaining wall material quantities.
Multiply the wall length by its total number of courses, then add a waste allowance. The calculator uses your block’s actual face length and height to provide a more accurate result.
Yes. The first course is normally partially or fully buried. Enter the planned buried depth so the calculator includes the additional block height in the total number of courses.
A 5 to 10 percent waste allowance is common for a simple straight wall. Curves, corners, steps and complex layouts may require 10 to 15 percent or more.
Many segmental wall projects use approximately 4 to 8 inches of compacted base material. Actual requirements depend on the wall system, soil, climate and manufacturer specifications.
Clean, angular and free-draining aggregate is commonly used behind the wall. Avoid material with excessive fines because it may restrict water movement.
No. The cost estimate covers only the listed materials. Excavation, delivery, labor, equipment, drainage pipe, adhesive, permits, geogrid and taxes are not included.
Proper drainage is important for most retaining walls because trapped water can create hydrostatic pressure. The exact drainage design depends on the wall height, soil, groundwater and local conditions.
Geogrid requirements depend on wall height, soil, slope and loads above the wall. Follow the block manufacturer’s design charts and consult a qualified engineer when necessary.