French Drain Trench Excavation, Washed Gravel Tonnage & Filter Fabric Calculator

Compute French drain gravel tons, spoil haul-off yd³, and burrito-wrap geotextile fabric.

Washed Drainage Gravel Needed
5.76 tons
Net Gravel Volume (Minus Pipe) 4.12 cu yd
Excavated Spoil Volume (Bank) 4.44 cu yd
Burrito-Wrap Geotextile Width 64 inches
Inputs
⚡ Scenarios:
ft
Total linear length of the French drain trench (ft).
inches
Trench width in inches.
inches
Trench depth in inches.
inches
Outside diameter of corrugated/PVC drain pipe (4.5" for 4" pipe).
Results & Graph
Washed Drainage Gravel Needed
5.76 tons
Net Gravel Volume (Minus Pipe)
4.12 cu yd
Excavated Spoil Volume (Bank)
4.44 cu yd
Burrito-Wrap Geotextile Width
64 inches

Washed Drainage Gravel Needed

Graph 1 • French Drain Gravel & Fabric • Domain Architecture & Live Telemetry Maps Drain Run Length Feet, Trench Width Inches, Trench Depth Inches through French Drain Gravel & Fabric Formula.
INPUT PARAMETERS • Drain Run Length F: 80 ft • Trench Width Inche: 12 inches • Trench Depth Inche: 18 inches ∑ F(x) French Drain Gravel & Fabr DESIGN OUTPUT 5.76 tons Net Gravel Volume (Minus: 4.12 cu yd Excavated Spoil Volume (: 4.44 cu yd
Graph 2 • Washed Drainage Gravel Needed Across Drain Run Length Feet Sweep (40% → 160%) Evaluates TrenchVol_ft³ = Length × Width × Depth; NetGravel_yd³ = (TrenchVol − P across 7 operating points (current input highlighted).
0 tons 5.07 tons 10.14 tons 2.31 32ft 3.46 48ft 4.61 64ft 5.76 80ft 6.92 96ft 8.07 112ft 9.22 128ft
Graph 3 • Joint Sensitivity: Drain Run Length Feet × Trench Width Inches Compares Washed Drainage Gravel Needed when Trench Width Inches is shifted +25% (solid) vs. −25% (dashed).
0 tons 5.24 tons 10.47 tons --- Trench Width Inches @ 75% 5.12 -30% 6.22 -15% 7.32 +0% 8.42 +15% 9.52 +30%
Summary: An 80 ft × 12" × 18" French drain excavates 4.44 cu yd of soil and requires 4.12 cu yd (5.76 tons) of washed #57 stone plus 64" wide filter fabric.
Summary: An 80 ft × 12" × 18" French drain excavates 4.44 cu yd of soil and requires 4.12 cu yd (5.76 tons) of washed #57 stone plus 64" wide filter fabric.
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Formula & Mathematical Methodology: French Drain Gravel & Fabric Formula

TrenchVolft³ = Length × Width × Depth
NetGravelyd³ = (TrenchVol − PipeVol) / 27
GravelTons = NetGravelyd³ × 1.4
TrenchVol_ft³ = Length × Width × Depth; NetGravel_yd³ = (TrenchVol − PipeVol) / 27; GravelTons = NetGravel_yd³ × 1.4
  • drainRunLengthFeet: Drain Run Length Feet (ft)
  • trenchWidthInches: Trench Width Inches (inches)
  • trenchDepthInches: Trench Depth Inches (inches)
  • perforatedPipeOuterDiaIn: Perforated Pipe Outer Dia In (inches)

Rounding: Engineering outputs round to 2–3 decimal places; discrete material bag/unit counts round up via ceiling.

Worked Example: Engineering Scenario: French Drain Gravel & Fabric

Compute French drain gravel tons, spoil haul-off yd³, and burrito-wrap geotextile fabric.

  1. Enter your system dimensions, electrical/RF ratings, or environmental conditions.
  2. Evaluate the governing equation: TrenchVol_ft³ = Length × Width × Depth; NetGravel_yd³ = (TrenchVol − PipeVol) / 27; GravelTons = NetGravel_yd³ × 1.4.
  3. Inspect the primary design output, supporting allowances, and 3 SVG schematics.
Result: Computes French Drain Gravel & Fabric via TrenchVol_ft³ = Length × Width × Depth; NetGravel_yd³ = (TrenchVol − PipeVol) / 27; GravelTons = NetGravel_yd³ × 1.4.

Frequently Asked Questions

How does the French Drain Trench Excavation, Washed Gravel Tonnage & Filter Fabric Calculator calculate results?

It evaluates TrenchVol_ft³ = Length × Width × Depth; NetGravel_yd³ = (TrenchVol − PipeVol) / 27; GravelTons = NetGravel_yd³ × 1.4 directly in your browser and updates three custom SVG visualizations in real time.

Can I use Goal Seek to solve backwards for a required dimension or rating?

Yes. Click "🎯 Goal Seek" in the results toolbar to solve backwards for any numeric input parameter.

Does this engineering calculator work offline?

Yes. All calculations run 100% locally in your browser and work offline via the CalculatorGraph PWA.

Construction & Home · Plumbing, Hydronics & Drainage

French Drain Trench Excavation, Washed Gravel Tonnage & Filter Fabric Calculator: inputs, method, and how to read the result

Compute French drain gravel tons, spoil haul-off yd³, and burrito-wrap geotextile fabric.

Choose inputs for the case you are checking

The defaults are illustrative. Replace them with values for your case and keep the units shown beside each field.

  • Drain Run Length Feet: Total linear length of the French drain trench (ft).
  • Trench Width Inches: Trench width in inches.
  • Trench Depth Inches: Trench depth in inches.
  • Perforated Pipe Outer Dia In: Outside diameter of corrugated/PVC drain pipe (4.5" for 4" pipe).

What the calculation includes

With the default values shown, Washed Drainage Gravel Needed is 5.76 tons. The calculation follows French Drain Gravel & Fabric Formula; the formula and variable definitions above show how the inputs combine.

One-input check: With the other defaults held constant, changing Drain Run Length Feet from 80 ft to 88 ft changes Washed Drainage Gravel Needed from 5.76 tons to 6.34 tons. This is a comparison inside the calculator's stated model, not a prediction.

Where to use caution

  • Uses standard NREL, IEEE, ASHRAE, and IRC design equations.
  • Verify final structural, electrical, and mechanical specifications against local building codes.

Scope: Global Engineering & Building Code Standard Check the assumptions and limitations against your situation before relying on the estimate.

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