Segmental wall material estimator
Retaining Wall Calculator
Estimate wall blocks and courses, cap blocks, compacted leveling base, drainage stone, drain pipe and material cost for one or more straight wall sections.
Material assumptions referenced to CMHA and manufacturer guidesUpdated
Project inputs
Measure the wall
Wall sectionsAdd each straight section with its average exposed height.
Wall units
Block and cap dimensions
Foundation
Leveling base
Drainage
Stone column and drain pipe
Optional material prices
Wall blocks to order170 blocks
For 30 ft of wall with up to 7 courses, including 5% block allowance.
Engineering review recommended
This input exceeds the calculator's 4 ft (1.2 m) planning threshold. Wall height, buried courses, slope, surcharge, water and soil conditions can require engineered reinforcement.
Retained soil
12 in drainage stone
7 block courses
6 in compacted base
Purchase checklist
Retaining wall material breakdown
| Material | Quantity | Unit price | Subtotal |
|---|---|---|---|
| Estimated material total | USD 1,357 | ||
Block core fill, adhesive, geotextile, geogrid, fittings, outlets, excavation, delivery, labor and taxes are not included unless represented by your entered prices.
Transparent math
How the retaining wall estimate is calculated
- 1Calculate courses for each wall section
ceil((36 in exposed + 6 in buried) / 6 in block) = 7 courses
- 2Count blocks in each course and add allowance
ceil(360 in / 16 in) x 7 courses x 1.05 = 170 blocks
- 3Calculate the compacted leveling base
30 ft x 2 ft x 0.5 ft x 1.10 = 33 ft³ = 2.29 US tons
- 4Calculate the drainage stone column
30 ft x 1 ft x 3.5 ft x 1.10 = 115.5 ft³ = 5.78 US tons
- 5Add wall length and outlet allowance for pipe
30 ft + 10 ft = 40 ft drain pipe
Planning assumptions
What this calculator can and cannot estimate
Wall geometry
Blocks are counted from their face dimensions. Setback, curves, corners, steps and product-specific bonding patterns can change actual quantities.
Base and drainage stone
The defaults use a 24 x 6 in leveling base and a 12 in drainage column as planning examples from manufacturer guidance. Approved plans and product instructions take priority.
Structural design
The tool does not check sliding, overturning, bearing, global stability, reinforcement length, surcharge, backslope, groundwater or seismic conditions.
Drainage is site-specific
CMHA notes that wall rock and a drain pipe handle incidental water; they are not a substitute for a designed surface and subsurface drainage system.
Common planning questions
Retaining wall calculator FAQ
Does wall height include the buried base course?
Enter the visible height separately. The buried depth is added when courses and drainage stone are estimated.
Why are blocks rounded by section?
Every straight section needs a whole number of blocks in every course. Calculating sections separately avoids using a partial leftover block across unrelated wall runs.
Does drainage stone include hollow block cores?
No. The result is the rectangular stone column behind the wall. Add product-specific core fill using the block manufacturer's coverage data.
Does the calculator determine geogrid?
No. Geogrid length and spacing depend on engineered wall geometry, soil, surcharge, slope, water and the selected block system.
When should an engineer review the wall?
Requirements vary by location and project. Taller walls, slopes, loads near the top, weak soil or water conditions should be reviewed before materials are ordered.