Retaining Wall Calculator
Estimate segmental wall blocks, caps, base gravel, drainage stone, and drain pipe from wall length and height.
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 list, not a build plan. Before you buy, make sure the wall size, block type, drainage, and local rules fit the job.
- Pick the block first, then check how tall that block can be used.
- Know the wall length, wall height, and how much block will sit below ground.
- Mark the trench width and gravel depth before ordering base material.
- Decide where the drain pipe will empty.
- For two-tier walls, check how far apart the tiers should be.
- If the wall holds back a slope, driveway, fence, or structure, get local guidance before buying.
- Check permits or engineering rules for tall walls before the material shows up.
Retaining wall calculator FAQ
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.
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.
When might local or engineering review be needed?
Height, soil, slopes, driveways, drainage, and local code can change what the wall requires. Check local rules and the block system guidance before you build.