How to use it
- Enter the trench length in feet
- Enter the width in feet
- Enter the depth in inches
- Click Calculate to see cubic feet, yards and tons
What it does – The calculator converts the length, width, and depth of your French drain trench into three useful measures: cubic feet, cubic yards, and approximate tons of rock. Why it matters – Knowing the exact volume prevents over‑ordering (which wastes money) or under‑ordering (which delays the project). How to read the results – Cubic feet is the raw volume; divide by 27 to see cubic yards, the standard unit for ordering rock. Multiply cubic yards by 1.4 to get the weight in US tons, useful for delivery quotes. The tool handles depth entered in inches, automatically converting it to feet before calculating. This eliminates manual conversion errors. Results are displayed to two decimal places, giving you a precise estimate while still being easy to round up for safety. You can also copy the numbers directly into a supplier’s order form, saving time. Accurate volume estimates also help you plan the amount of sand or geotextile needed, ensuring a well‑functioning drainage system.
Pro tips
- Add 10% extra rock to cover settling
- Round up cubic yards to the nearest whole number for ordering
- If supplier quotes by weight, use the 1.4 tons per cubic yard conversion
- Double‑check depth measurement; an inch error can change volume significantly
Real-life examples
- Homeowner preparing a new backyard French drain wants exact rock quantity
- Landscape contractor estimating material for a municipal sidewalk drainage project
- DIY renovator replacing an old drain and needs to match previous rock volume
Case study
Maria needed a French drain for her soggy yard. She entered a 40‑ft length, 2‑ft width, and 8‑in depth into the calculator and got 4.94 cubic yards (≈6.9 tons). She ordered 5 cubic yards, avoiding a costly over‑order and completed the project on schedule.