French Drain Cost Calculator
Estimate the cost to install a French drain from its length and your material and labor rates per linear foot.
How this calculator works
French drain cost scales with how far the trench runs, so this calculator multiplies your drain’s length by a material rate and a labor rate, both priced per linear foot. Both rate fields are editable placeholders — swap in numbers from a real quote for an accurate estimate.
Formula: Total cost = drain length × material rate per ft + drain length × labor rate per ft.
Worked example
A 50 ft French drain, $6/ft material, $8/ft labor:
- Drain length: 50 ft
- Material cost: 50 × $6 = $300
- Labor cost: 50 × $8 = $400
- Total estimated cost: $700
Notes
Material cost covers the perforated pipe, gravel, and filter fabric. Labor is typically the larger cost driver, since trenching is hand or machine dug at the right slope — about 1% minimum — for gravity flow to work. A longer run, or one that has to navigate around existing landscaping or hardscape, raises labor time well above a straight, open-yard run.
How to use
Enter your French drain’s total length along with your material and labor rates per linear foot. The calculator multiplies length by each rate and adds them together for a total estimated cost — replace the default rates with numbers from a local quote for a more accurate figure.
Estimates only. Actual cost depends on your region, trench depth, and site obstacles — get a contractor quote before budgeting.
Frequently asked questions
What does the material cost cover in this estimate?
Material cost covers the perforated pipe, gravel backfill, and filter fabric that make up a French drain. It's calculated as your drain's total length times a material rate per linear foot, which you can edit to match a supplier quote.
Why is labor often the larger cost in a French drain install?
Trenching has to be dug — by hand or machine — at the right slope, typically at least about 1% grade, for gravity to actually move water through the drain. That digging and grading work is usually the larger driver of total cost compared to the materials themselves.
Does this estimate account for obstacles in the yard?
No, it uses a flat rate per linear foot. A trench that has to navigate around existing landscaping, hardscape, or other obstacles takes more labor time than a straight run through open yard, which raises the real cost above a flat per-foot estimate.
What slope does a French drain need to work?
A French drain generally needs a consistent downhill slope toward its outlet, with about 1% minimum grade being a common reference point, so water moves by gravity instead of pooling in the trench.
Estimates only. Verify quantities with your supplier before purchasing.