Retaining Wall Calculator — ft, blocks, cost
How to use this calculator
Select wall type (landscape blocks, poured concrete, or timber/railroad ties), enter wall length and height, then configure materials and drainage. Results update instantly with material quantities, courses, drainage requirements, and cost.
Blocks — choose standard (12×4×8″) or large (18×6×12″) landscape blocks with setback per course.
Concrete — tapered gravity wall with top/base thickness and optional rebar.
Timber — 6×6 or 6×8 railroad ties with deadman anchors.
Drainage — gravel backfill, drain pipe, filter fabric, and geogrid for walls over 4 ft.
Saved Calculations
| Time | Type | L×H | Material | Gravel | Cost |
|---|
How to Calculate Materials for a Retaining Wall
This retaining wall calculator estimates materials for three wall types: landscape/segmental blocks, poured concrete (gravity), and timber/railroad ties. Enter wall length and height in feet and inches, select block size or concrete thickness, and configure drainage. Results include block count (with courses), concrete volume in cubic yards, or timber count, plus gravel backfill tonnage, drain pipe, filter fabric, and geogrid requirements.
Landscape Block Walls
Standard blocks (12×4×8″, ~30 lbs) for walls up to 4 ft. Large blocks (18×6×12″, ~65 lbs) for taller walls. Setback of ¾″ per course provides batter for stability. Walls over 4 ft require geogrid reinforcement per NCMA guidelines.
Drainage Requirements
Proper drainage is critical for all retaining walls. A 12″ gravel backfill behind the wall with a 4″ perforated drain pipe at the base and filter fabric prevents hydrostatic pressure buildup. Gravel weight: approximately 1.35 tons per cubic yard (100 lb/ft³).
FAQ
How tall can I build without engineering? Most jurisdictions allow gravity walls up to 4 ft without a permit. Walls over 4 ft typically require engineering drawings and geogrid reinforcement.
How much gravel do I need behind a retaining wall? Standard practice is 12″ of clean crushed gravel behind the wall, extending the full height. This calculator computes the exact tonnage.
