Free tool
Retaining Wall Calculator
Enter the wall size and your block dimensions — get the block count, courses, and blocks per course, with a waste factor built in. Free, no signup for the estimate.
Blocks needed
0 blocks
- Wall face area0 ft²
- Courses0
- Blocks per course0
- With waste0
- Estimated cost—
Turn takeoffs into paid jobs
Get the free Job Pricing Kit — a printable pricing worksheet, the markup & margin cheat-sheet, and clean invoice + quote templates so the job you just measured becomes a professional quote. We’ll email it now.
Free PDF. No spam. Unsubscribe anytime.
✓ Check your inbox — the kit is on its way.
Or download it now (PDF)How to calculate retaining wall blocks
A segmental retaining wall comes down to face area and how much one block covers — plus a little extra for cuts. Get the wall size right, work out the block’s coverage from its length and height, and add waste, and you order the right pallet instead of stopping a course short of the top.
1. Measure the wall face
Multiply wall length × height in feet to get the exposed face area in square feet. For a wall that steps up or down a slope, break it into sections, figure each, and add them. Measure the visible face you’re building, not including the buried base course beyond what you count.
2. Find each block’s coverage
Multiply the block’s length × height in inches and divide by 144 for square feet of face per block. An 18 × 6 in block covers 0.75 sq ft. The calculator turns that into a block count for whatever unit you enter.
3. Check courses and blocks per course
Courses are the wall height ÷ block height; blocks per course are the wall length ÷ block length, rounded up. The calculator shows both so you can confirm the layout works out to whole courses before you order.
4. Add a waste factor
Ends, corners, and curves all mean cut blocks, and the odd unit cracks — about 10% covers it, more for a serpentine or tiered wall. Buy the allowance with the job, since block color varies between runs and a later top-up may not match.
Measuring the job is step one. Turning it into a priced, professional quote is faster inside CrewRivet. See the gravel calculator, the paver calculator, or the job pricing calculator.
Retaining wall calculator FAQ
- How many blocks do I need for a retaining wall?
- Multiply the wall length by its height to get the face area, work out how much one block’s face covers from its length and height in inches, add about 10% for cuts and breakage, and divide. This calculator does all of it, and also shows the number of courses and blocks per course once you enter your block size.
- How do I figure courses and blocks per course?
- Courses are the wall height in inches divided by the block height — a 24 in wall of 6 in blocks is 4 courses. Blocks per course are the wall length in inches divided by the block length, rounded up. Multiply the two and you have the wall total; the calculator shows each number so you can sanity-check the layout.
- Do I need a cap course and base?
- Most segmental walls finish with a cap course (often glued on) and sit on a compacted gravel base with a buried first course for stability. This calculator counts the wall blocks; add cap units separately and plan your gravel base (our gravel calculator helps).
- How much waste should I add?
- About 10% covers cuts at the ends, corners, and any curve, plus the odd cracked block. Add more for a serpentine or tiered wall with lots of cuts. Buy the allowance with the job — block color varies between production runs, so a later top-up may not match.
- Is the calculator free?
- Yes — the live estimate is free with no email required. Enter your email only if you want the free Job Pricing Kit (pricing worksheet, markup cheat-sheet, and invoice + quote templates) sent to your inbox.