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Retaining Wall Calculator

Count exact retaining-wall field units for a reviewed straight-wall course schedule, then reconcile explicit allowance, matching stock and supplier packs.

Use this result well

Inputs that matter
Measured straight wall run, reviewed total whole courses including any buried course, one exact selected field-unit installed module, explicit field-unit allowance, usable matching stock, and exact current field units per supplier pack
Output to expect
Whole field units per course, base and allowance-adjusted demand, stock applied, new demand, whole supplier packs, available units and visible surplus
How it works
Round the straight-run module count to whole field units, multiply by the reviewed course schedule, apply only the entered allowance, subtract compatible stock, then round only new demand to exact supplier packs
  • Verify the exact selected system, installed module, total course/run schedule, connections, cuts, corners, curves, steps, tapers, caps, mixed units, lots and current packaging; nominal face dimensions are not an approved layout.
  • Obtain responsible design and jurisdiction review for soil, height, loads, groundwater, base, drainage, core/backfill aggregate, geogrid, global stability, excavation, permits and inspection; this field-unit count approves none of them.

Choose your path

Built around the job you need to finish

Count one exact standard field-unit product for a reviewed straight constant-run segmental retaining wall, then reconcile visible allowance, matching stock and current supplier packs without pretending to design the wall system.

Homeowner reconciling an approved small-wall layout

Turn a known straight run and course schedule into a transparent field-unit purchase count.

Copy the total course count, including any buried course, and the exact selected product's installed horizontal module.

Sees whole units per course, base demand and explicit allowance separately without fabricated caps, gravel or adhesive.

Landscape buyer using matching stock

Use verified leftover standard units before ordering current whole packs.

Confirm the exact product, size, finish, connection and lot requirements, then enter compatible stock and supplier pack quantity.

Stock is capped at reserve, new demand cannot go negative, and pack surplus stays visible.

Contractor reviewing a complex or engineered wall

Prevent a field-unit count from being mistaken for wall design or a complete material takeoff.

Keep changing runs, specialty units, caps, base, drainage, reinforcement, soil, load and jurisdiction requirements in their responsible reviewed schedules.

The record explicitly declines to approve geometry, stability, drainage, geogrid, permits or inspection.

Authoritative checks for this tool

Outputs and checklists are planning aids. Review the linked current authorities and the records, terms, instructions, and requirements that apply to your exact situation before a consequential decision.

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Reference & details

How it works

Exact field units per course

Use one selected system's installed field-unit module. Nominal block-face dimensions do not establish a pattern, connection, setback, corner, curve or cut schedule.

Units per course = ceil(Straight run × 12 ÷ Exact installed horizontal module)

Reviewed course schedule and allowance

Copy the whole course count, including any buried course, from the responsible plan or exact system review. The allowance is visible and user-entered; zero adds none.

Reserve field units = ceil(Units per course × Reviewed total courses × (1 + Entered allowance%))

Stock and supplier packs

Apply only compatible whole stock, then round new demand to the current exact supplier pack. Available units and surplus remain visible.

Packs = ceil((Reserve field units − Usable matching stock) ÷ Exact field units per pack)

Updated: August 2026

Example Scenarios

Use the measured run, exact installed module and reviewed total course count for one standard field-unit SKU. The example keeps a buried course visible because it is entered, not inferred from height.

Verify product, size, finish, connection and lot requirements before counting leftover field units. The tool caps applied stock at the reserve and rounds only remaining demand to packs.

Do not pool corners, curves, steps, tapers, caps, multi-size patterns or changing course runs into this straight field-unit record. Build separate reviewed schedules for those products and segments.

Common Mistakes to Avoid

Dividing wall face area by a nominal block face

Use the exact installed field-unit module and reviewed course schedule for one selected wall system.

Treating a field-unit count as a complete wall design

Obtain separate approved schedules for geometry, specialty units, base, drainage, soil, reinforcement, loads, permits and inspection.

FAQ

Visible height alone does not establish buried courses, steps, tapers, system setback or the approved wall configuration. Enter the whole course count from the responsible plan or exact system review.

Use the exact selected product's installed horizontal module. Manufacturer dimensions, connections, setback and pattern rules vary; nominal face arithmetic is not an approved layout.

No. Those are different products with their own modules, cuts, packaging and installation requirements. Reconcile each through a separate reviewed schedule.

No. CMHA guidance makes soil, loads, geometry, groundwater, drainage and the specific unit-reinforcement system design-dependent. Obtain approved requirements and quantities separately.

Before relying on a material count, confirm the exact system instructions, site conditions, local code/permit requirements and whether responsible engineering is required. This calculator does not set a universal height threshold.

About Retaining Wall Calculator

Create an auditable purchase count for one exact standard field-unit product on a straight, constant-run segmental retaining wall. Enter the measured run, the total whole courses already established by the responsible plan or system review, the exact installed horizontal module, an explicit field-unit allowance, usable matching stock and the current supplier pack quantity. The result does not design the wall or invent caps, aggregate, drainage, reinforcement or adhesive.