Hardscape · Free Tool

Retaining wall material calculator.

Block count, base aggregate, drainage gravel, drain pipe, and geogrid for a segmental retaining wall (SRW). Includes the buried course math you forget every time. Residential-grade — over 4 ft exposed needs an engineer.

Inputs

Above-grade height. Adds 1″ buried per 8″ exposed automatically.

6″ residential · 8″ frost-prone or weak soil.

12″ of 3/4 clear standard. Plus a perforated drain at base.

8% standard · 5% straight runs · 12-15% curves and stairs.

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Wall face area
146.7
sqft

Includes 1 buried course.

SRW blocks
159
units

Includes 8% waste. Order full pallets — count up.

Cap blocks
42
units

One per linear foot + 5%.

Base aggregate (3/4 clear)
1.5
cubic yards

≈ 2.1 tons · 24″ wide trench × 6″ deep.

Drainage gravel (3/4 clear)
5.5
cubic yards

≈ 7.7 tons · 12″ chimney behind wall.

Perforated drain pipe
42
linear ft

4″ socked, daylighted at lowest point.

Cap adhesive
2
tubes

SRW-rated polyurethane. ~25 lf per tube.

Field notes. Compact base in 2″ lifts. Set the first course dead level — every hour spent on the bottom course saves a day on top. Always backfill drainage gravel as you go up, not at the end. For walls over 4 ft exposed: get the engineer drawing, build to it, keep it on file. Frost line in southern Ontario is 48″ — bury accordingly if the wall supports a structure.
Material list — ready to order

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SRW blocks
159units
Cap blocks
42units
Base aggregate (3/4 clear)
1.5cu yd
Drainage gravel (3/4 clear)
5.5cu yd
Perforated drain pipe
42lin ft
Cap adhesive
2tubes
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