French Drain Cost Calculator

Worked example

With these inputs:

• Units: Feet and inches
• Drain length (ft or m): 60
• Trench width (in or cm): 12
• Trench depth (in or cm): 18
• Perforated pipe: 4 in (100 mm)
• Topsoil/sod over the stone (in or cm): 3
• Washed #57 stone, delivered: 45 $/ton
• Pipe price: 1.2 $/ft
• Filter fabric: 0.25 $/sq ft
• Outlet (pop-up emitter, dry well…): 40 $
• Trencher rental: 200 $/day
• Feet you can trench per day: 150
• Contractor labor + equipment: 30 $/ft
• Extra stone: 10 %

Prices are editable assumptions, not quotes. Slope the drain at least 1% (1 in per 8 ft) to the outlet, call 811 before digging, and check whether your town needs a permit to discharge water near a property line.

How it works

This prices a French drain the way it is built: stone sized around the pipe, the perforated pipe, filter fabric to wrap the trench, and the outlet. It then compares doing it yourself with a rented trencher against paying a contractor per foot, and gives the cost per linear foot for each. Every price is editable — put in your local quotes.

Frequently asked questions

How much does a French drain cost per foot?

Materials alone usually run a few dollars a foot: stone, perforated pipe and fabric. With the default prices a 60 ft, 12 × 18 in drain costs about $9 a foot DIY including a one-day trencher rental, and about $36 a foot with contractor labor at $30/ft. Deep drains, rocky soil, hand digging and replacing hardscape all push the installed price up.

Is a French drain worth doing yourself?

For a shallow yard drain in diggable soil, often yes: the trencher rental and materials are a fraction of installed labor. Foundation (footing) drains, deep trenches and drains near utilities are better left to a contractor.

What adds the most to French drain cost?

Labor and access. Digging by hand, removing and replacing concrete or pavers, rocky or clay soil, depth beyond about 2 ft and a dry well instead of a daylight outlet all add cost.

How much gravel does a French drain need?

About 0.05 cubic yards per foot for a 12 in wide, 18 in deep trench with a 4 in pipe and no soil cap — roughly 2.6 cubic yards or 3.7 tons for 50 ft. The French drain gravel calculator works out stone, pipe and fabric in detail.

Do I need a permit for a French drain?

Usually not for a yard drain on your own property, but many towns regulate where the water may discharge — not onto a neighbor's lot or the sidewalk. Check with your local building or public works department.