French Drain Calculator
Result
French Drain Calculator Calculate gravel volume and perforated pipe length for a French drain installation. — free online calculator.
Formula
- French Drain Calculator calculates its result from Drain Length, Trench Width, Trench Depth, Slope. It uses the formula Volume (cu yd) = L × W × D ÷ 27; Slope: 1% minimum (1 in drop per 8.3 ft). Change any input to recalculate the result instantly.
- The main inputs are Drain Length, Trench Width, Trench Depth, Slope. Enter them in the units and format shown in the calculator.
- Keep measurements and project assumptions consistent before comparing or combining values.
- Changing any input above recalculates the result with the same calculation engine used by this page.
Example: French Drain
- Drain Length: 40
- Trench Width: 1.5
- Trench Depth: 2
- Slope: 1
For a 40 ft × 1.5 ft × 2 ft drain: gravel 120/27=4.4444 cu yd, estimated weight 6.2222 tons at 1.4 tons/yd³, pipe length 40 ft and 1% slope drop 4.8 inches.
Sample result: Calculating…
Frequently asked questions
What does the French Drain calculate?
French Drain Calculator Calculate gravel volume and perforated pipe length for a French drain installation. — free online calculator.
Which values should I enter?
Enter Drain Length, Trench Width, Trench Depth, Slope using the units and format shown beside each field.
What formula does this calculator use?
The calculator uses the following relationship: Volume (cu yd) = L × W × D ÷ 27; Slope: 1% minimum (1 in drop per 8.3 ft).
Why might my result differ from another source?
Results can differ when another source uses different units, rounding rules, conventions or assumptions. Compare the inputs and definitions before comparing results.
Does the result update automatically?
Yes. Changing an input updates the result using the same calculation engine shown on this page.