Do I need filter fabric?
Yes, lining the trench with geotextile fabric prevents soil from clogging the gravel and pipe.
Calculator
Enter your values
Results
Gravel Needed
2.62 yd³
Est. Weight
3.66 tons
Pipe Length
50 ft
Filter Fabric
200.0 sq ft
Analysis
Interpretation of the current calculator output
Calculation Summary
The current inputs have been processed for the french drain calculator. Review the results panel for the computed output and use the charts tab to compare the current values visually.
How to Read It
The main result shows the direct answer for your current inputs. Supporting sections below explain the method, example, and common questions so the result is easier to interpret.
How to Use
Step-by-step instructions
- 1Enter the length of the drain (feet).
- 2Enter the trench width and depth (inches).
- 3The calculator will estimate gravel and fabric needs.
Trench Volume
Calculates the volume of the trench minus the volume occupied by the pipe to determine gravel needs.
Gravel = (Trench Vol - Pipe Vol) × DensityVariables:
LTrench LengthWTrench WidthDTrench DepthExample
Backyard Drain
Inputs:
Length:50 ft
Width:12 in
Depth:18 in
Steps:
- 1.Trench Vol = 50 × 1 × 1.5 = 75 cu ft
- 2.Pipe Vol ≈ 4.4 cu ft
- 3.Gravel Vol = 70.6 cu ft = 2.6 cy
- 4.Weight = 2.6 × 1.4 = 3.6 tons
Result:
2.6 cy gravel, 3.6 tons