Measure Twice › Landscaping & yard
Retaining Wall Calculator
Enter your wall's length, height and block size to get the blocks, caps and gravel to build it properly.
Worked example
- Wall length 30 ft
- Exposed wall height 3 ft
- Block length (face) 18 in
- Block height 8 in
- Buried courses 1
- Cap blocks on top Yes
- Gravel levelling pad depth 6 in
- Levelling pad width 24 in
- Drain rock behind the wall 12 in
Result:
- Wall blocks (incl. 5% extra)
- 126 blocks
- Cap blocks
- 21 caps
- Courses (incl. buried)
- 6 courses
- Blocks per course
- 20 blocks
- Levelling pad gravel
- 1.7 tonnes
- Drain rock (clear stone)
- 4.44 yd³
- Drain rock weight
- 5.1 tonnes
- Perforated drain pipe
- 30 ft
Lay a perforated drain pipe along the back of the bottom course, wrapped in fabric, sloped to daylight.
Load this example into the calculator
How the retaining wall calculator works
It counts how many rows of blocks reach your exposed height, adds the buried course(s), and multiplies by the blocks needed along each row. Underneath, a compacted gravel levelling pad supports the wall. Behind it, a zone of clear drain rock and a perforated pipe let water escape, which is what keeps most walls from failing.
courses = exposed height ÷ block height (rounded up) + buried courses
blocks = courses × (wall length ÷ block length) × 1.05
levelling pad = wall length × pad width × pad depth × 1.25
drain rock = wall length × drain zone depth × total wall height
Tips
- Height limits: walls over about 4 ft (1.2 m) generally need an engineered design and a permit, and often geogrid reinforcement. Walls near property lines or holding up a driveway may need one sooner. Check with your municipality.
- Get the first course right. It must be level and fully on compacted gravel; every mistake there shows up at the top.
- Use the manufacturer’s numbers. Block sizes, setback and maximum heights vary by system.
- Never backfill with clay right behind the wall. Use clear stone so water drains down to the pipe.
Where to buy in Metro Vancouver
Local suppliers we've checked. Nobody pays to be listed. Call ahead for prices, minimums and delivery to your area.
Retaining wall block and pavers
- Meadows Landscape Supply in Pitt Meadows
Topsoil, bark mulch, gravel, sand, pavers and wall block, delivered across Greater Vancouver and the Fraser Valley.
- North Shore Landscape Supply Centre in North Vancouver
Road base, clear crush, soils and mulch, plus Belgard, Barkman and other wall block. Flat-fee delivery.
- Barkman Concrete Products in Surrey
Manufacturer of pavers, slabs and retaining wall block.
Gravel, sand and soil (bulk)
- Meadows Landscape Supply in Pitt Meadows
Topsoil, bark mulch, gravel, sand, pavers and wall block, delivered across Greater Vancouver and the Fraser Valley.
- North Shore Landscape Supply Centre in North Vancouver
Road base, clear crush, soils and mulch, plus Belgard, Barkman and other wall block. Flat-fee delivery.
Related calculators
- Gravel Calculator
Enter the area and depth to see how much gravel, sand, soil or mulch to order, in bulk or bags.
- Concrete Patio Calculator
Replacing grass with concrete? Enter the slab size to get every layer, from how deep to dig to how much ready-mix to order.
- Fence Calculator
Enter your fence length and design to get posts, rails, pickets and the concrete to set the posts.
Last updated October 28, 2026