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Drainage Rock Calculator

Estimate drainage rock volume, tons, delivery, and cost for French drains, trench drains, dry wells, retaining wall drainage, swales, and drainage beds.

Common drainage rock uses

  • • French drain trenches
  • • Retaining wall backfill drainage
  • • Dry well stone beds
  • • Yard drainage swales
  • • Drainage pipe bedding
  • • Landscape drainage zones

Drainage Rock Calculator

Enter trench dimensions in feet and inches. Results update instantly for rock volume, tons, fabric, pipe length, delivery, and estimated cost.

Estimated drainage materials

Trench area75.00 sq ft
Gross trench volume112.50 ft³
Pipe displacement4.36 ft³
Net rock volume108.14 ft³
Cubic yards4.01 yd³
Cubic yards with waste4.41 yd³
Estimated tons5.95 tons
Estimated fabric275.00 sq ft
Estimated pipe length52.50 ft
Truckloads0.59 loads
Material cost$387
Delivery$95

Estimated total

$482

About $10 per linear foot.

This estimate subtracts pipe displacement from the trench volume, then adds waste. Confirm trench slope, outlet location, filter fabric, pipe type, and local drainage requirements before ordering.

Drainage rock formula

Cubic feet = length × width × depth

Cubic yards = cubic feet ÷ 27

Tons = cubic yards with waste × tons per cubic yard

Estimated cost = tons × price per ton + delivery

Typical drainage rock depths

ProjectTypical depth
French drain12–24 inches
Retaining wall drainage12–24 inches behind wall
Dry well stone bed18–36 inches
Landscape drainage bed4–12 inches

Drainage rock FAQ

How much drainage rock do I need?

Multiply length by width by depth to get cubic feet. Divide by 27 for cubic yards, then multiply by the material density to estimate tons. Add waste for uneven trenches, settlement, and ordering tolerance.

Should drainage rock be washed?

Clean washed stone is usually better for drainage because fines and dust can reduce water flow. For French drains, use suitable drainage fabric to help keep soil out of the stone.

Does this calculator include pipe or fabric?

No. This calculator estimates drainage rock only. Pipe, fittings, filter fabric, excavation, labor, disposal, and permits should be estimated separately.