French Drain Calculator for Gravel, Pipe, and Fabric

Estimate gravel needed, pipe length, trench volume, and filter fabric coverage for a basic french drain.

Unit System

Choose the measurement style you want to use.

Waste Allowance

Adds extra material for overlap, compaction, and cuts.

Trench Length

Enter total drain run in feet.

Enter a trench length greater than 0.

Trench Width

Enter trench width in inches.

Enter a trench width greater than 0.

Trench Depth

Enter trench depth in inches.

Enter a trench depth greater than 0.

Pipe Diameter

Typical perforated pipe is 4 inches.

Enter a pipe diameter greater than 0.

This calculator is built for quick material estimates only. It does not calculate slope, drainage flow, or project cost.

Gravel needed

Pipe length

Filter fabric

Trench volume

Results include your selected waste allowance.

If you are planning a drainage project, these tools can help you get more accurate estimates:

Use the Gravel Calculator to double-check how much gravel you need for your trench.
Try the Cubic Yard Calculator to convert trench volume into cubic yards easily.
Measure your trench area first with the Square Footage Calculator before calculating materials.
Explore more Construction Calculators for similar building and material estimation tools.

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