Does this include buried courses?

No. Add embedded/buried courses to wall height to account for them in the block count.

How accurate is the backfill volume?

It uses a simple 0.5 ft thickness. Your design may need more or less depending on wall height and drainage details.

Do I need geogrid or drainage?

Most walls do. This calculator doesn’t include them—follow manufacturer specs and local code for reinforcement and drainage pipe.

Can I use this for curved walls?

Yes, but increase waste since curved cuts consume more blocks.

Is this engineering-approved?

No. It’s a planning estimate only. Taller walls need an engineer’s design and local permit approval.

construction calculator

Retaining Wall Calculator

Estimate block count, caps, and backfill volume for a retaining wall.

Results

Blocks needed: 264.00
Cap blocks (approx): 33.00
Backfill gravel (cubic yd, est.): 2.96

How to use this calculator

Enter wall length and height in feet and block size in inches.
Set a waste allowance for cuts and breakage.
See total block count, cap blocks, and an estimated gravel backfill volume.

Inputs explained

Wall length: Overall wall length in feet.
Wall height: Visible wall height in feet (add buried courses separately if needed).
Block length/height: Dimensions of the wall block in inches.
Waste allowance: Extra percentage for cuts, breakage, and pattern staggering.

How it works

Blocks per course = wall length ÷ block length.

Courses = wall height ÷ block height. Waste adds a buffer.

Backfill volume is a rough estimate using a 0.5 ft thickness behind the wall.

Formula

Blocks = (Length/block length) × (Height/block height) × (1 + waste)

When to use it

Estimating block and cap counts before ordering pallets.
Budgeting base and backfill material for small retaining walls.
Communicating rough quantities to clients before engineering sign-off.

Tips & cautions

Include buried/embedded courses to match manufacturer guidance; adjust height to cover them.
Drainage (gravel + pipe) is critical—ensure you plan for it beyond the rough backfill estimate.
Increase waste for curved walls or complex step-downs.
Backfill is a rough 0.5 ft thickness estimate; real designs vary.
Does not include geogrid, drainage pipe, or engineering requirements.
Structural walls over local height limits require professional design—this is a material estimate only.

Worked examples

40 ft × 4 ft wall, 16×6 in blocks, 10% waste

Blocks ≈ 272
Caps ≈ 33

20 ft × 3 ft wall, 12×6 in blocks, 8% waste

Blocks ≈ 160
Caps ≈ 22

Deep dive

This retaining wall calculator estimates block counts, cap blocks, and gravel backfill. Enter wall length, height, block size, and waste to plan pallets before meeting with an installer or engineer.

Use it for segmental walls and garden terraces, then layer on drainage, geogrid, and code requirements separately. Increase waste for curves or heavy cutting patterns.

FAQs

Does this include buried courses?: No. Add embedded/buried courses to wall height to account for them in the block count.
How accurate is the backfill volume?: It uses a simple 0.5 ft thickness. Your design may need more or less depending on wall height and drainage details.
Do I need geogrid or drainage?: Most walls do. This calculator doesn’t include them—follow manufacturer specs and local code for reinforcement and drainage pipe.
Can I use this for curved walls?: Yes, but increase waste since curved cuts consume more blocks.
Is this engineering-approved?: No. It’s a planning estimate only. Taller walls need an engineer’s design and local permit approval.

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Retaining walls need proper engineering, drainage, and geogrid per local code.