Whole courses, not just face area
A fraction of a course still needs a course. The worksheet rounds each dimension up before multiplying, so its block count can differ from wall area divided by block area.
Measure the wall, count the courses
Retaining wall calculator
Count whole courses first. For example, a 24 ft wall with a 30 in exposed height and 16 × 6 in block faces needs 5 courses × 18 blocks: 90 wall blocks before allowance.
Enter your own dimensions below. This worksheet separates wall blocks, optional caps and base volume, then adds only the quote prices you supply. It does not count buried courses or price a complete installed wall.
Rows and blocks visibleBase dimensions explicitOptional cap countNo login or usage limit
01 Measure02 Enter product facts03 Count and compare
Rows = exposed height ÷ block face height, rounded up · blocks per row = wall length ÷ block face length, rounded up · blocks = rows × blocks per row, then the entered allowance · base volume = length × base width × base depth
Count, then compare
The retaining wall math, with units shown
Use one straight, constant-height wall run. Read installed block face dimensions from the product documentation and base dimensions from the project plan. Do not use the block depth as its face height.
Caps stay separate
Enter a cap length to count one row along the wall. It does not replace a wall course. The result does not apply allowance to caps or include their price.
Base is not drainage backfill
Base volume is the rectangular strip under the wall. Gravel behind the wall, buried blocks and reinforcement are separate quantities. The worksheet does not choose their dimensions.
US dimensions: courses = ceil(height in ÷ block height in); blocks per course = ceil(length ft × 12 ÷ block length in); wall blocks = ceil(courses × blocks per course × (1 + allowance % ÷ 100)). Base cu yd = length ft × base width in × base depth in ÷ 3,888.
Metric dimensions: wall length uses m, all smaller dimensions use cm. Base m³ = length m × base width cm × base depth cm ÷ 10,000. A cap count is rounded up separately.
Dimension reference: the manufacturer’s Alta Wall specifications list 6 in height, 16 in width and 12 in depth as different measurements. The example here uses face height and width, not block depth. Use your own product specifications and project plan; burial, base and reinforcement requirements are not selected here.
Check one run
A block count and quote you can audit
This is a hypothetical arithmetic example, not a recommended wall design or a current supplier price.
- Exposed courses: 30 in ÷ 6 in = 5. Blocks per course: 24 ft × 12 ÷ 16 in = 18. That gives 90 wall blocks.
- Your allowance: with 10% entered, ceil(90 × 1.10) = 99 wall blocks. A separate 16 in cap length gives 18 caps, with no cap allowance.
- Base strip: 24 ft × 12 in × 6 in ÷ 144 = 12 cu ft, or 12 ÷ 27 = 0.444 cu yd. Width and depth are example inputs, not installation advice.
- Entered quote subtotal: at a hypothetical $5 per wall block, $54 per cu yd of base and $40 delivery, the subtotal is $495 + $24 + $40 = $559. Caps and every unentered or excluded cost are still outside it.
Checking metric? A 6 m run, 60 cm exposed height and 40 × 15 cm block face gives 4 courses × 15 = 60 wall blocks before allowance. A 50 cm × 10 cm base strip gives 0.300 m³. The result also shows cubic yards because the base price input uses that unit.
Need the full purchase quantity? Check buried courses, cap cuts, corner units, stepped runs, drainage aggregate and supplier order rules separately. A poured concrete wall also needs thickness and structural details this tool does not collect.
Before you order
Retaining wall calculator questions
How many retaining wall blocks do I need?
Round exposed height divided by block face height up to whole courses. Round wall length divided by block face length up to whole blocks per course. Multiply them, apply your allowance and round up. Use matching units in each division.
Does this include buried blocks or stepped walls?
No. The height input counts exposed courses only. Buried courses, corners, curves and changes in height need a separate quantity check against the project plan.
How are cap blocks counted?
Cap count is wall length divided by cap block length, rounded up. Caps are separate from the wall block count. The planning allowance is not applied to caps, and there is no cap price input.
Can this work as a retaining wall cost calculator?
It calculates a subtotal for the prices you enter: wall blocks, the calculated base volume at USD per cubic yard, and delivery. Blank prices stay unknown. The subtotal excludes cap prices, drainage, reinforcement, excavation, labor and taxes.
Is this an installed retaining wall cost estimate?
No. It is a quantity worksheet and entered-price subtotal, not an installed quote. Supplier minimum orders, order increments and compaction adjustments are not applied to base volume.
Can this calculate a poured concrete retaining wall?
No. It can count concrete wall blocks using their installed face dimensions. It does not calculate poured concrete volume, formwork, reinforcement or structural design.
How is the base volume calculated?
For US inputs, base cubic yards equal wall length in feet times base width in inches times base depth in inches, divided by 3,888. For metric inputs, base cubic meters equal wall length in meters times base width in centimeters times base depth in centimeters, divided by 10,000.
Does switching to metric convert my entered values?
No. Re-enter dimensions after switching units. Metric uses meters for wall length and centimeters for height, block faces, base width, base depth and cap length. Quote prices remain USD, and base price remains USD per cubic yard.
Do I need to log in or register?
No. This free retaining wall calculator runs in your browser without login, registration or a usage limit.
Connect the project
Keep related material quantities separate
Use the fence calculator for fence panels and posts, or the gravel calculator for base aggregate, landscape rock and supplier order rules. Each page keeps its own measured inputs and formulas visible.