What a 150 ft French drain takes
| Item | Amount |
|---|---|
| Drain rock (clean washed stone, 3/4 to 1½ in) | 8.63 cubic yards, 12.1 tons |
| Perforated pipe, 4 in | 150 ft (15 pieces of 10 ft) |
| Non-woven filter fabric | 750 sq ft |
| Soil to dig out | 8.3 cubic yards |
For a trench 12 in wide and 18 in deep, with 10% extra stone for uneven trench walls and settling. The stone is the trench volume less the space the pipe takes up, at 1.4 tons per cubic yard.
150 ft of drain, by trench size
Width × depth of the trench, with a 4 in pipe and 10% extra stone.
| Trench | Drain rock, cubic yards | Tons | Fabric, sq ft | Soil dug out, cubic yards |
|---|---|---|---|---|
| 8 × 12 in | 3.54 | 5.0 | 550 | 3.7 |
| 12 × 12 in | 5.58 | 7.8 | 600 | 5.6 |
| 12 × 18 in | 8.63 | 12.1 | 750 | 8.3 |
| 12 × 24 in | 11.69 | 16.4 | 900 | 11.1 |
| 18 × 24 in | 17.80 | 24.9 | 975 | 16.7 |
A narrower trench saves stone on a long run
Over 150 ft the width of the trench is worth thinking about. At 18 in deep, a trench 8 in wide takes 5.6 cubic yards (7.8 tons), 12 in wide 8.6 cubic yards (12.1 tons) and 18 in wide 13.2 cubic yards (18.5 tons).
Every inch of width you do not dig is stone you do not buy. The trench still has to be wide enough to bed a 4 in pipe with stone on both sides.
Use clean, washed stone with no fines, wrap the stone (not the pipe) in the fabric, and make sure the drain has an outlet. The fittings, tools and steps are in the French drain materials list, and the method behind the stone figure is in how much gravel for a French drain.
Want to change anything else? The calculator above is the full French Drain Calculator: edit any number and the results update instantly.
Tools & materials for this project
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Frequently asked questions
How much gravel do I need for a 150 foot French drain?
About 8.6 cubic yards, or 12.1 tons, of clean drain rock for a trench 12 in wide and 18 in deep with a 4 in pipe, including 10% extra. A 12 by 24 in trench takes 11.7 cubic yards.
How wide should a French drain trench be?
Wide enough to bed the pipe with stone on both sides. Over 150 ft, 8 in wide takes 7.8 tons of stone and 12 in wide 12.1 tons, both at 18 in deep.
How much pipe for a 150 ft French drain?
150 ft of perforated pipe, which is 15 pieces of 10 ft, plus couplers if you use sticks.
Related sizes and guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.