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Retaining Wall Gravel Calculator

Estimate the drainage gravel backfill needed behind a retaining wall. Enter the wall length, backfill width and height for cubic yards and tons.

Retaining Wall Gravel Calculator

$
0
backfill (yd³)
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tons
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cubic feet
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est. cost
Retaining Wall Gravel Calculator, live preview
depth
Enter values to see your estimate.

How to Calculate Retaining Wall Gravel

Change the calculator above and watch every figure and the diagram below update live.

Top-down view (area × depth)

W L depth 4"

Step 1 · Area

20 ft × 10 ft = 200 ft²

Step 2 · Volume (× depth, ÷ 27)

200 ft² × 0.33 ft ÷ 27 = 2.47 yd³

3.46
tons (× 1.4)
134
bags (÷ 0.5 ft³)

These figures update automatically as you change the calculator above.

Backfill gravel coverage

Approximate coverage of one cubic yard of gravel at common depths.

Approximate coverage of one cubic yard of gravel at common depths.
DepthCoverage per yd³Relative coverage
1" 324 sq ft
100%
2" 162 sq ft
50%
3" 108 sq ft
33%
4" 81 sq ft
25%
6" 54 sq ft
17%
3 in
3"

At 3 inches deep, one cubic yard of gravel covers 108 sq ft.

Retaining Wall FAQs

How much gravel do I need behind a retaining wall?
Multiply wall length × backfill width × height (in feet) and divide by 27. A 12-inch-wide drainage zone is common behind block walls.
What gravel goes behind a retaining wall?
Clean, angular drainage stone like #57 lets water escape and relieves pressure on the wall.
How wide should the gravel backfill be?
At least 12 inches of gravel directly behind the wall, paired with a perforated drain pipe at the base.
Why is drainage gravel important?
It stops water building up behind the wall, the main cause of retaining-wall failure.

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