Blocks by the face area
Segmental retaining wall blocks show a 16-inch face and stand about 6–9 inches high depending on the system; the calculator counts courses by height and blocks per course by length. Every course buried (the first is set below grade) is still a block you buy — add buried courses to the height.
Backfill is half the material bill
A retaining wall is a drainage system that happens to hold soil: 1 foot of clean gravel behind the entire wall, with a perforated drain pipe at the base, is what keeps hydrostatic pressure from pushing it over. The calculator returns that gravel volume — order it along with the blocks, and cap blocks per linear foot.
Sources and standards
Where these figures come from
Every formula on this page is implemented from the published reference material below. Where a value depends on a regional code, the calculator lets you override it rather than assuming one jurisdiction.
- ASTM International — C94 for ready-mixed concrete, C150 for cement and C143 for slump testing.
- American Concrete Institute — ACI 318 code requirements and ACI 302 slab construction guidance.
- Portland Cement Association — mix design, yield and curing data published by the US cement industry.
Figures, formulas and reference tables last verified: 19 September 2026.