Retaining wall block calculator
Estimate retaining-wall blocks, cap units, courses, and base gravel from wall length, exposed height, and block size.
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Tool guide
Retaining wall block calculator: how it works
Practical information to understand the result and use this tool correctly.
About Retaining wall block calculator
Order volume is wall length divided by the block face length, rounded up per course, times exposed courses plus buried courses, then times a small waste allowance. Exposed courses are the exposed height divided by the block height, rounded up. Cap units use the cap length the same way, without the course stack.
A typical garden wall buries the first course so the face starts below grade. Set buried courses to 0 only if the manufacturer allows a wall that sits fully on the prepared base. Base gravel is length × trench width × trench depth, with the same waste factor, reported in cubic meters or yards.
Presets cover a 6 m garden wall with 40×20 cm blocks, a low seat wall, a 20 ft run of 12×4 in landscape blocks, and a taller 1 m face. Switching meters and feet converts length, height, block size, cap length, and the trench.
Nothing is uploaded. This is a material list, not a structural design. Walls over about 1 m (3–4 ft), slopes, surcharge, or poor soil need an engineer and the block maker’s limits. Brick counts a mortared wall; concrete sizes a pour; fence counts posts.
How to use it
- 1Choose meters or feet and a preset, or enter wall length and exposed height.
- 2Set block face length and height, cap length, and how many courses are buried.
- 3Add a waste allowance and the gravel trench width and depth.
- 4Review courses, blocks, caps, base gravel, and optional cost, then copy the order.
Frequently asked questions
- How are retaining wall blocks calculated?
- Blocks per course are wall length divided by block face length, rounded up. Total blocks are that count times exposed courses plus buried courses, times (1 + waste), rounded up. Exposed courses are exposed height divided by block height, rounded up.
- Should I bury a course?
- Most landscape-block guides bury at least the first course. The default is one buried course. Use the manufacturer sheet if the block is a pinned or lip system with a different embedment.
- Does this design the wall?
- No. It only counts blocks, caps, and base gravel. It does not size geogrid, drainage pipe, or footing concrete, and it is not a substitute for an engineer on tall or loaded walls.
- Does the calculation leave the browser?
- No. Lengths, block sizes, prices, and the order summary stay on your device.