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Retaining Wall Calculator

Updated Aug 24, 2026 Reviewed Aug 24, 2026

Estimate courses, blocks, caps, aggregate, core fill, drain pipe, user-specified geogrid, and optional material cost.

Retaining-wall material takeoff

Enter wall, block, drainage, and plan dimensions

Wall length

Exposed wall height

Wall unit

Block and cap settings

Block face length

Block face height

Block depth

Block unit

Buried courses

Block allowance (%)

Include one cap row

Cap face length

Cap unit

Base, drainage, and core fill

Aggregate base width

Aggregate base depth

Drainage-zone depth behind wall

Horizontal thickness of the entered drainage zone.

Aggregate dimension unit

Core-fill volume per block

Enter zero for solid units or unfilled cores.

Core-fill volume unit

Aggregate allowance (%)

Drain-pipe allowance (%)

User-specified geogrid

Do not infer reinforcement here

Only enter layer count and embedment length supplied by a qualified design.

Geogrid layers

Embedment length per layer

Geogrid length unit

Result volume unit

Result length unit

Result area unit

Optional material prices

Currency

Price per block

Price per cap

Aggregate price per m³

Drain-pipe price per m

Geogrid price per m²

Material takeoff only — not structural design

Does not check sliding, overturning, bearing, global stability, water, soil, slopes, surcharge, seismic loads, permits, or system compatibility.

Result

Calculation summary

Enter values to see the result

Your result, breakdown, assumptions, and warnings will appear here.

Wall assembly preview

Blocks, base, drainage, and pipe

Live preview

The drawing is schematic; entered product and project dimensions govern the takeoff.

How to use this calculator

1Enter wall and actual product dimensions.
2Enter buried courses and approved aggregate dimensions.
3Enter geogrid only from qualified design and optional supplier prices.

Formula

Blocks = ceil(length ÷ block length) × (ceil(height ÷ block height) + buried courses) × (1 + waste)

Courses and units round up; aggregate zones are calculated separately.

Calculation steps

Normalize dimensions.
Round courses and blocks.
Add buried courses and allowance.
Calculate aggregate and pipe.
Total only entered geogrid.

Worked example

A 10 m by 1 m exposed wall with 40 cm × 20 cm blocks uses five exposed courses before buried courses.

Assumptions

Not structural or drainage design.
Wall is level and uniform.
Aggregate dimensions come from the plan.
Geogrid is never inferred.
Soil, water, loads, slopes, and seismic effects are outside scope.

Sources

Frequently asked questions

Does this determine geogrid?

No. It totals only layers and lengths from qualified design.

Why include buried courses?

Many systems require them; use product instructions and the plan.

Does aggregate include block cores?

Only when core-fill volume per block is entered.

Can it calculate stepped walls?

Only roughly; divide into level segments and verify course layout.

When is professional review needed?

Whenever required locally or when height, soil, water, slopes, seismic effects, or loads affect stability.

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