French Drain Calculator
Size a French drain for a soggy yard or a downspout run: trench volume, drainage stone, perforated pipe and filter fabric, with the materials cost.
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Estimated cost
$375 – $630
Typical figure around $503.
- Trench volume
- 2.8 cu yd
- Drainage stone
- 4 tons
- Perforated pipe
- 50 linear ft
- Filter fabric
- 300 sq ft
Stone, 4-inch perforated pipe and fabric. Keep a 1% fall so water runs away from the house.
Planning estimate only — confirm quantities with your supplier or contractor before ordering.
How this estimate is calculated
The estimate is built from drain length (ft), trench width (in), trench depth (in) and drainage stone, then priced at national average rates. It reports trench volume, drainage stone, perforated pipe and filter fabric, with quantities rounded up so you are never short of material and the standard waste allowance already included where it applies.
Stone, 4-inch perforated pipe and fabric. Keep a 1% fall so water runs away from the house.
The dollar range is a national average, so treat it as a starting point rather than a bid. Labor rates, permit fees and material delivery differ by region — the state table below shows how your state compares, and construction cost by state breaks the picture down further.
Prefer the longer version? Read our guide to How much does a gravel driveway cost.
Cost by drainage stone
Each row prices the same default job shown in the calculator above, changing only the drainage stone. Use it to see what the upgrade or the cheaper option really costs before you commit.
| Drainage stone | Low | High |
|---|---|---|
| Crushed stone (#57) | $375 | $630 |
| Washed river rock | $433 | $719 |
What the same job costs by state
Every row applies that state's construction cost index to the national range calculated above. The index bundles local labor rates, permit fees and material delivery, so it is a planning figure rather than a bid.
| State | Index | Low | High |
|---|---|---|---|
| Ohio | 0.92 | $345 | $580 |
| Texas | 0.93 | $349 | $586 |
| North Carolina | 0.94 | $353 | $592 |
| Georgia | 0.95 | $356 | $599 |
| Arizona | 1.01 | $379 | $636 |
| Florida | 1.02 | $383 | $643 |
| Pennsylvania | 1.03 | $386 | $649 |
| Illinois | 1.05 | $394 | $662 |
| Colorado | 1.08 | $405 | $680 |
| Washington | 1.15 | $431 | $725 |
| California | 1.32 | $495 | $832 |
| New York | 1.42 | $533 | $895 |
Index 1.00 is the national average. See construction cost by state for metro-level figures and the projects homeowners ask about most.
Where to buy materials
Links to suppliers are sponsored: if you buy through them, we may earn a commission at no extra cost to you. It never affects an estimate.
- Search The Home Depot“perforated drain pipe french drain”
- Search Lowe's“perforated drain pipe french drain”
Frequently asked questions
How deep should a French drain be?
Deep enough to intercept the water: usually 18 to 24 inches to the top of the pipe, with the pipe sitting on a 1% slope. Shallow drains work for surface water, deep ones for a high water table.
What stone goes in a French drain?
Washed stone sized between 3/4 inch and 1 1/2 inch (such as #57 crushed stone) so it stays open. Never use sand, limestone dust or pea gravel, which clog the pipe over time.
How much does a French drain cost?
A 50 ft drain 12 inches wide and 24 inches deep takes about 4 tons of crushed stone, plus 50 ft of perforated pipe and filter fabric. That is roughly $375 to $630 in materials, and most of the total is stone rather than pipe.
Do I need a French drain or a dry well?
A French drain moves water somewhere — to a daylight outlet, a storm system or a lower part of the yard. A dry well stores it in one spot and lets it soak away, so it fails on ground that already stays saturated.
Does this cost change from state to state?
Yes. Applying each state's construction cost index to the national range of $375 to $630, the same job runs from about $345 to $580 in Ohio (index 0.92) to $533 to $895 in New York (index 1.42).
What is not included in this estimate?
Stone, 4-inch perforated pipe and fabric. Keep a 1% fall so water runs away from the house. The figure is a national planning average for the work described above, not a contractor's quote.
