BuildToolsHub US Construction Calculators

Masonry & Brick

Retaining Block Calculator

Estimate interlocking retaining wall blocks by face area.

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Educational US estimate only. Not engineering, structural, code, or professional construction advice. Mix designs, codes, and local conditions vary — verify with licensed professionals and your building department.

Estimator methodology

BuildToolsHub takeoffs separate net measured quantities from ordered quantities. Ordered qty = net × condition-based waste, then rounded for plant or package sizes (e.g. ready-mix to the nearest 0.5 yd³).

  • Concrete bags: Quikrete / SAKRETE published yields (80 lb ≈ 0.60 ft³). Ready-mix contingencies follow ASTM C94 purchaser practice.
  • Rebar: CRSI published lb/ft tables; optional lap allowance ≈ 40× bar diameter (confirm with drawings).
  • Roofing: NRCA squares (100 ft²); pitch factor √(1+(rise/12)²); ~3 bundles/square for standard shingles.
  • Aggregates / fill: ASTM C29-style densities; swell/compaction allowances for haul and place volumes.
  • Masonry: BIA / NCMA common unit factors (e.g. ~1.125 CMU/ft² for 8×16 face).

Use the Order tab for a supplier call sheet and the Assumptions panel for the exact factors applied to this run.

Why use Retaining Block Calculator

Plan landscaping and small retaining walls by entering face length and height for unit counts.

Geogrid, drainage, and gravity limits are design issues—verify manufacturer charts for height.

How to use

  1. Enter job dimensions. Pick a pour/layout condition to set industry waste %, or choose Custom.
  2. Review Net vs Order on the Summary tab — order the rounded quantity, not net alone.
  3. Open the Order tab for a supplier checklist, then print, export CSV, or share the link.

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About Retaining Block Calculator

Do these blocks need mortar?

Many segmental walls are dry-stacked with pins; follow the product system.

How high can I go?

Depends on block system, soil, and surcharge. Check manufacturer max heights.

Include buried base course?

Yes—buried courses still consume blocks; add them to height.

Is this professional engineering advice?

No. Educational estimates only. Verify with a licensed professional and local codes.

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