Plan your French drain project with precision using our free online calculator. Quickly estimate the required volumes of gravel (cubic yards), length of perforated pipe (linear feet), and filter fabric (linear feet & width) needed to manage excess water and prevent landscape damage. Get started today and ensure effective drainage!
Formula:
French Drain Calculation Formulas
Here are the formulas used to calculate the materials for your French drain project:
- Trench Volume (Cubic Feet):
Trench Length (ft) × (Trench Width (in) / 12) × (Gravel Depth (in) / 12) - Gravel Volume (Cubic Yards):
Trench Volume (cf) / 27 - Pipe Length (Linear Feet):
Trench Length (ft) - Filter Fabric Length (Linear Feet):
Trench Length (ft) - Filter Fabric Width (Inches):
Trench Width (in) + (2 × Gravel Depth (in))
Where:
- Trench Length: The total length of your planned French drain trench.
- Trench Width: The desired width of your trench.
- Gravel Depth: The total depth of gravel fill in your trench (from the bottom up).