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French Drain Gravel, Fabric & Pipe Calculator

Calculate cubic yards and tons of #57 washed drain stone gravel, perforated pipe footage, non-woven geotextile drainage fabric width, and trench excavation volume.

Standard: 12" width for yard drains, 18" for heavy runoff

Calculation Results

Washed #57 Gravel Required: 3.8 Tons (2.8 cu yds) Clean Washed Round Stone or Crushed Granite (No Fines)
Non-Woven Geotextile Fabric Width: 4 ft or 5 ft Wide Roll Total Fabric Needed: ~325 sq ft
Perforated Pipe Length to Order: 70 Linear Feet (with fittings)
Total Soil Excavated: 3.6 Cubic Yards

About This Calculator

Calculate cubic yards and tons of #57 washed drain stone gravel, perforated pipe footage, non-woven geotextile drainage fabric width, and trench excavation volume.

Frequently Asked Questions

Why must you use non-woven geotextile drainage fabric instead of weed barrier?

Woven landscape weed barrier fabric quickly blinds and clogs with clay silt particles within months, causing water to pool on top. Non-woven 4 oz needle-punched geotextile fabric acts as a high-flow permeable filter that allows water to pass through freely while permanently stopping soil from invading the gravel.

What size gravel is specified for French drains?

Clean washed #57 stone (3/4-inch to 1-inch crushed granite or river rock without stone dust or fines) is the universal engineering standard. The large voids between stones allow rapid subterranean water percolation.

Should perforated pipe holes face up or down in a French drain?

Holes MUST face DOWN. As water rises into the gravel trench from below, it enters the bottom holes and drains away immediately. Turning holes upward forces the trench to completely fill with water before draining.

Why is rigid smooth-wall PVC superior to corrugated black pipe?

Smooth-wall PVC (Schedule 40 or SDR-35) has 50% less hydraulic friction, moves water faster, resists root crushing, and can be easily cleared with a drain snake or hydrojetter without tearing.