French Drain Calculator — Gravel & Pipe

How does the french drain calculator work?

Gravel volume = trench length × width × depth (all in ft), converted to cubic yards. Pipe length equals trench length + 10%. Fabric wraps the trench bottom and sides.

What else do people ask about this calculator?

How deep should a French drain be?

Typical residential drains are 18–24 in deep, with the perforated pipe pitched 1% (1 in per 8 ft).

Do I need filter fabric?

Yes — wrapping the trench in geotextile keeps soil out of the gravel and stops the drain from silting up.

Which related calculators should I use next?

Gravel

Estimate gravel by area and depth in tons or cubic yards.

Mulch

Estimate mulch in bags and cubic yards for any bed size.

Topsoil

Estimate topsoil in cubic yards and tons for any project.

Sod

Estimate sod in square feet, rolls and pallets.

Where can I learn more about these materials?

Weights, coverage, types and buying tips for the materials this calculator estimates.

Gravel guide

How much gravel you need, what a yard weighs, and which type fits your project.

Crushed Stone guide

#57, #8, ¾″ minus — which crushed stone goes where.

All calculators