Free civil tool · Metric · No signup
Retaining Wall Calculator
High-level quantities for pricing a retaining wall — face area, excavation, drainage aggregate, plus posts, concrete or blocks by wall type.
Example inputs are editable. Use your project values. Enter 0 where no optional allowance is intended; blank fields pause the calculation.
Your inputs
Your results
- Wall face area
- 24 m²
- Excavation behind wall (bank)
- 14.4 m³
- Drainage aggregate
- 7.2 m³
- Backfill (excavation − aggregate)
- 7.2 m³
- Posts required
- 15
- Post length each (height + embedment)
- 2.4 m
- Rail / lagging face area
- 24 m²
These free results do not automatically save or sync to a Fieldlink job.
How it works
- Face area = length × height
- Excavation = length × excavation width × height
- Drainage aggregate = length × aggregate width × height
- Posts = ceiling(length ÷ maximum spacing) + 1 for a non-zero straight run
- Concrete = face area × thickness
- Blocks = face area × blocks per m²
Worked example
20 m × 1.2 m timber wall @ 1.5 m spacing Face 24 m² · posts 15 · drainage metal 7.2 m³
Assumptions and practical notes
Quantities only, not structural design. Use the project design for spacing, embedment and sections. Straight-run post count includes both ends; corners, returns, openings, footings and reinforcement are not modelled.
Working on the full job?
Price the quantities from the project design with your own rates.