Retaining Wall Calculator
Estimate segmental wall blocks, caps, base gravel, drainage stone, and drain pipe from wall length and height.
Need wall length first?
Use the distance tool on the satellite map to measure your wall line, then enter the length here.
How the estimate is calculated
Each tier is estimated as its own wall run, then material totals are summed. Base gravel, drainage stone, and pipe use the assumptions you set above.
Courses = exposed height ÷ block height, rounded up, plus buried courses
Wall blocks = blocks per course × courses + buffer
Caps = each tier length ÷ block running length, rounded up, then summed
Base gravel = wall length × base width × base depth
Drainage stone = wall length × backfill zone × (height − 6 in soil cap)
Before you order
Use this as a shopping estimate. Confirm tier spacing, drainage, reinforcement, and local requirements before buying.
- Confirm spacing or setback between tiers.
- Check whether upper tiers load lower tiers.
- Plan a drainage outlet for each tier.
- Use the block maker height chart.
- Check local requirements for 4 ft+ or complex sites.
Retaining wall calculator FAQ
How do I calculate retaining wall blocks?
Enter the wall length, exposed height, and block size. The calculator estimates blocks per course, courses high, buried base courses, and extra blocks for waste.
How many cap blocks do I need?
Cap blocks are estimated from each tier length divided by the block running length, rounded up, then summed. Verify cap length and cuts with the block guide.
How much base gravel does a retaining wall need?
Multiply wall length by base width and depth for a cubic-foot total, then convert to cubic yards. Many segmental walls use 4–6 inches of compacted gravel — use your block spec if it differs.
How much drainage stone goes behind a retaining wall?
The estimate uses wall length, exposed height, and the backfill width behind the wall. Wider zones hold more stone; narrow ones hold less.
When does a retaining wall need engineering or manufacturer review?
It depends on height, soil, and local code. Taller walls, slopes, driveways, or poor drainage often trigger permit or engineering review — check before you build.
Can I estimate a tiered retaining wall?
Yes. Add each tier as its own wall run. The calculator totals materials across tiers; confirm tier spacing, drainage, and reinforcement with the block guide.
Measure the wall line
Use the map distance tool for curved or uncertain runs before estimating blocks, caps, gravel, and drainage.