HOW TO USE IT
How to use the French Drain Cost Calculator
- 1
Enter the drain length, depth and trench width in feet.
- 2
Choose the perforated pipe size.
- 3
Set gravel, filter fabric and soil type.
- 4
Review the total cost and line-item breakdown.
THE MATH
French drain cost formula
Total = pipe + gravel + fabric + labor + disposal4 in perforated pipe runs ~$1.80/ft, 6 in ~$2.50/ft. Labor averages ~$12 per cubic ft dug and rises with soil (clay x1.15, rocky x1.45) and access.
PRACTICAL EXAMPLE
60 ft × 2 ft × 1 ft trench, clay soil, moderate access
Volume = 60 × 2 × 1 = 120 ft³. Pipe = $108. Gravel = $1,200. Fabric = $48. Labor = 120 × $12 × 1.15 × 1.1 = $1,822. Disposal = $120. Total ≈ $3,300.
FAQ
Frequently asked questions
How much does a French drain cost in 2026?
Use $10-$25/ft as an initial planning allowance, then price the actual trench volume, soil, access and outlet.
How deep should it go?
Depth depends on the water source, slope and outlet; define the drainage profile for the site.
Is filter fabric necessary?
The filter detail depends on soil and aggregate; confirm the intended drainage section.