Retaining Wall Block Calculator – Blocks, Cost & Concrete (Free)
Free retaining wall block calculator — find how many blocks you need, footing size, and total cost. Covers block walls, poured concrete, precast, and circular retaining walls
Retaining Wall Block Calculator: Blocks, Footing, Concrete & Cost
Four-mode calculator covering straight block walls, circular retaining walls, footing & concrete quantities, and full cost comparison across block, poured concrete, and precast options.
For a standard 20-foot retaining wall built 3 feet high using 12"×6" landscape blocks, you need approximately 120 blocks plus 7–10% waste — about 129 blocks total. This retaining wall block calculator gives you that answer instantly along with three more calculator modes: a circular wall block calculator, a footing and concrete calculator, and a full wall cost estimator.
Mode B answers the retaining wall block circle calculator question directly — a query with almost no dedicated free tool online. Mode A also includes a built-in face feet calculator sub-section, since block pricing and quantities are always based on face square footage. Mode D compares landscape block, CMU/cinder block, poured concrete, and precast wall costs side by side.
Below the calculator you'll find three professional diagrams — a wall elevation view, a circular plan view, and a cost comparison chart — plus full reference tables for block counts, footing concrete, and installed pricing. Select a calculator mode below or use the reference tables and diagrams for quick planning.
Blocks Needed
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Face Sq Ft
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Courses × Per Course
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All Block Sizes Comparison
Enter the outer diameter (or radius) of your circular retaining wall.
Total Blocks (Circular Wall)
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Circumference
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Per Course × Courses
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Total Concrete Needed
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Footing Concrete
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80lb Bags (Footing)
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Core Fill / Wall Pour
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Mortar (60lb bags)
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Total Estimated Cost
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Cost / Face Sq Ft
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Face Sq Ft
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All Wall Types — Installed Cost Comparison
Block counts are estimates based on standard block face dimensions. Actual quantities depend on block manufacturer specifications, mortar joint thickness, and waste on site. Cost estimates are 2024–2025 national averages — always get local contractor quotes.
Typical retaining wall construction showing running-bond block pattern, cap blocks, footing below grade, and filter fabric behind wall. Dimensions vary by project.
How many retaining wall blocks do I need — the formula
Direct answer: To find how many retaining wall blocks you need, multiply your wall length (in feet) by your wall height (in feet) to get the face area in square feet, then multiply by the blocks-per-square-foot for your block size. For standard 12"×6" landscape blocks, that is 2 blocks per square foot.
Blocks per square foot — all common block sizes
| Block size | Face area | Blocks per face sq ft |
|---|---|---|
| Standard landscape (12"×6") | 0.50 ft² | 2.0 |
| Large landscape (18"×6") | 0.75 ft² | 1.33 |
| CMU / cinder block (16"×8") | 0.889 ft² | 1.13 |
| Mini landscape block (6"×4") | 0.167 ft² | 6.0 |
Block count reference table (standard 12"×6" landscape blocks, with 7% waste)
| Wall Length | Height 2 ft | Height 3 ft | Height 4 ft | Height 6 ft |
|---|---|---|---|---|
| 10 ft | 21 | 32 | 43 | 64 |
| 15 ft | 32 | 48 | 64 | 96 |
| 20 ft | 43 | 64 | 86 | 128 |
| 30 ft | 64 | 96 | 128 | 193 |
| 40 ft | 86 | 128 | 171 | 257 |
| 50 ft | 107 | 161 | 214 | 321 |
The product of wall length × wall height is called "face feet" or "face square feet" — this is the measurement used to order retaining wall blocks, calculate material costs, and design wall drainage. All retaining wall pricing is quoted per face square foot.
Face feet calculator — what is a face foot and how to calculate it
Direct answer: A face foot (or face square foot) is one square foot of visible wall surface area. It is calculated by multiplying wall length by wall height: Face sq ft = length (ft) × height (ft). All retaining wall materials are quoted in face square feet or face square yards.
| Wall length | Height 1 ft | Height 2 ft | Height 3 ft | Height 4 ft | Height 6 ft |
|---|---|---|---|---|---|
| 10 ft | 10 | 20 | 30 | 40 | 60 |
| 15 ft | 15 | 30 | 45 | 60 | 90 |
| 20 ft | 20 | 40 | 60 | 80 | 120 |
| 25 ft | 25 | 50 | 75 | 100 | 150 |
| 30 ft | 30 | 60 | 90 | 120 | 180 |
| 40 ft | 40 | 80 | 120 | 160 | 240 |
| 50 ft | 50 | 100 | 150 | 200 | 300 |
To convert face square feet to face square yards: divide by 9.
Circular retaining wall plan view showing 8-foot diameter with 24–26 blocks per course. The circumference formula (π × diameter) determines how many blocks fit each course. Use the Circular Wall tab in the calculator above.
Circular retaining wall block calculator — how to calculate a round wall
Direct answer: To calculate blocks for a circular retaining wall, first find the circumference of the circle (π × diameter), then divide by the block length to get blocks per course. Multiply blocks per course by the number of courses (wall height ÷ block height) for the total block count.
| Diameter | Circumference | Blocks/course | 2 ft high | 3 ft high | 4 ft high |
|---|---|---|---|---|---|
| 4 ft | 12.57 ft | 13 | 26 | 52 | 78 |
| 6 ft | 18.85 ft | 19 | 41 | 61 | 81 |
| 8 ft | 25.13 ft | 26 | 112 | 84 | 111 |
| 10 ft | 31.42 ft | 32 | 69 | 103 | 137 |
| 12 ft | 37.70 ft | 38 | 81 | 122 | 163 |
| 15 ft | 47.12 ft | 48 | 103 | 154 | 206 |
| 20 ft | 62.83 ft | 63 | 135 | 203 | 270 |
Most standard landscape retaining wall blocks are designed with tapered sides that allow them to create curves naturally. The minimum radius achievable depends on block length — typically a 4-foot diameter minimum for 12-inch blocks. For tighter curves, use shorter blocks.
Contractor-installed cost per square foot varies significantly by wall type and region. DIY installation typically reduces cost by 40–60%. See the Wall Cost Estimator tab for your project.
How much does a concrete wall cost — block, poured, and precast prices
Direct answer: The cost of a concrete or block retaining wall ranges from $15 to $70 per face square foot installed, depending on the wall type. Landscape block walls are typically the least expensive ($15–$35/sq ft). Poured concrete walls cost $30–$60/sq ft. Precast concrete panels run $20–$45/sq ft installed.
| Wall type | DIY materials/sq ft | Installed/sq ft | 60 sq ft total (installed) | Notes |
|---|---|---|---|---|
| Landscape block | $3–$8 | $15–$35 | $900–$2,100 | Most DIY-friendly |
| CMU / cinder block | $5–$12 | $20–$40 | $1,200–$2,400 | Needs core fill + mortar |
| Poured concrete | $10–$18 | $30–$60 | $1,800–$3,600 | Formwork required |
| Precast panels | $15–$25 | $20–$45 | $1,200–$2,700 | Fast install |
| Natural stone | $15–$30 | $30–$70 | $1,800–$4,200 | Premium look |
60 sq ft = 20 ft × 3 ft wall (common residential retaining wall size).
Poured concrete retaining wall cost
A poured concrete retaining wall is the most structurally rigid option — concrete is poured into temporary forms that are removed after curing. Contractor cost is typically $30–$60 per square foot including forming, reinforcing, pouring, and finishing. The price for poured concrete walls is driven largely by form rental and labour — DIY is difficult without experience.
Precast concrete wall cost
Precast concrete walls and panels are fabricated off-site and delivered as finished units. Precast concrete walls cost $20–$45 per square foot installed — faster to install than poured concrete but limited in custom sizing. Precast concrete building panels run $25–$55 per square foot. Large precast retaining wall blocks (Redi-Rock, Jensen Precast) cost $30–$60 per square foot installed.
Block wall cost
A standard landscape block retaining wall costs $15–$35 per square foot installed. CMU/cinder block walls cost $20–$40 per square foot — slightly more than landscape blocks due to mortar and core fill requirements. Both are significantly cheaper than poured or precast for residential retaining walls under 4 feet.
Regional variation note
Gulf Coast and Northeast US markets run 10–18% above national averages. For Louisiana, Florida, and Texas: add 10–15% to the table above. For New York, Massachusetts, and New Jersey: add 15–20%.
Concrete for cinder block and block walls — fill and footing guide
Direct answer: For a cinder block (CMU) retaining wall, you need two types of concrete: footing concrete (poured below grade to support the wall) and core fill concrete (poured into the hollow cores of the blocks for strength). For landscape retaining wall blocks (Allan Block, Versa-Lok), only footing concrete is needed — these blocks do not have hollow cores.
| Wall length | Footing 12"×8" | Footing 16"×10" | Footing 24"×12" |
|---|---|---|---|
| 10 ft | 0.25 cy (5 bags) | 0.41 cy (7 bags) | 0.74 cy (14 bags) |
| 20 ft | 0.49 cy (9 bags) | 0.82 cy (15 bags) | 1.48 cy (27 bags) |
| 30 ft | 0.74 cy (14 bags) | 1.23 cy (22 bags) | 2.22 cy (40 bags) |
| 40 ft | 0.99 cy (18 bags) | 1.65 cy (30 bags) | 2.96 cy (54 bags) |
V_ft³ = footing width (ft) × footing depth (ft) × wall length (ft). 80lb bags = ceil(V ÷ 0.60).
Core fill for CMU block walls (per 100 standard 8"×8"×16" blocks)
| Fill type | Concrete needed |
|---|---|
| Partial fill (every other core) | ~0.25 cy |
| Full grout (all cores) | ~0.50 cy |
| Mortar (standard joints) | 8 bags (60lb) |
Retaining wall block calculator — frequently asked questions
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The most complete free retaining wall calculator
This tool covers straight block walls, circular walls, footing and concrete quantities, CMU core fill, and cost comparison across all five wall types — landscape block, CMU, poured concrete, precast, and natural stone. It includes a dedicated face feet calculator sub-section and three professional visual diagrams to help you plan with confidence.
Use the free Retaining Wall Block Calculator above — select your mode and get your block count, footing specs, and cost estimate instantly.