✓ ASTM D4751 Drainage Geotextile Standard
French Drain Trench & Gravel Calculator
Calculate washed #57 drainage stone (tons/cu yds), 4" perforated pipe, and geotextile filter fabric rolls.
Trench Dimensions & Specifications
Drainage Material Checklist
Washed #57 Gravel 3.66 Tons 2.62 Cubic Yards
4" Perforated Pipe 50 Ft Smooth-wall or Corrugated
Non-Woven Geotextile Fabric (4-6 oz): 250 sq ft (4ft × 65ft roll)
Excavated Soil to Remove: 3.5 cu yds of dirt
Frequently Asked Questions
How deep and wide should a French drain trench be?
A standard residential yard French drain trench should be 12 inches wide and 18 to 24 inches deep. This leaves room for a 2-inch gravel bedding, a 4-inch perforated drain pipe, and 12+ inches of drainage gravel wrapped in filter fabric.
What type of gravel is best for a French drain?
Use washed #57 crushed stone or 3/4-inch to 1-inch smooth river rock. Never use crusher run, stone dust, or pea gravel with fines, as fine particles will wash into the pipe and clog the drain.
Do I need non-woven filter fabric for a French drain?
Yes! Wrapping the entire gravel trench and pipe in heavy non-woven geotextile fabric (4 oz or 6 oz) is the single most important step to prevent soil and silt from clogging the drainage rock over time.