Fill Dirt Calculator
Calculate the volume, weight in tons, and dump truckloads of fill dirt needed for grading, trench backfill, and foundation build-ups.
Calculation Results
Total cubic yards of loose dirt needed to achieve final compacted grade.
Total volume in cubic feet.
Total shipping weight in short tons (2,000 lbs/ton).
Standard residential tandem delivery trucks (approx. 10 cubic yards each).
Large commercial tri-axle dump trucks (approx. 15 cubic yards each).
How This Calculator Works
Estimate fill dirt deliveries accurately with these steps:
- Measure the Fill Area: Enter the average length, width, and depth of the hole, slope, or foundation trench.
- Select Soil Characteristics: Choose standard clean fill, sandy loam, or heavy clay to calibrate weight and hauling costs.
- Set Compaction Factor: 15% is standard for structural backfill to prevent sinking over time.
- Review Delivery Takeoff: Get exact cubic yards, weight in tons, and the number of 10-yard or 15-yard dump trucks needed.
Formula & Calculations
Fill dirt calculations determine in-place geometric volume adjusted for mechanical or natural soil compaction:
1. In-Place Volume Formula
Raw Volume (cu ft) = Length (ft) × Width (ft) × Depth (ft)
2. Compaction & Shrinkage Settlement
When subsoil is excavated and dumped, it fluffs up with air pockets. Once placed, compacted with a roller or vibratory plate, and settled by rain, it compacts significantly:
- Standard Foot Traffic / Gravity: 10% to 15% settlement.
- Mechanical Vibratory Compaction: 15% to 25% compaction.
Compacted Volume = Raw Volume × (1 + Compaction Factor / 100)
3. Weight Conversion
Clean fill dirt weighs between 2,400 and 3,000 pounds per cubic yard (1.2 to 1.5 tons/yd). Moist clay soil is substantially heavier than dry sandy loam.
Step-by-Step Calculation Examples
Foundation Perimeter Backfill (30ft x 10ft x 12in)
Backfilling a 1-foot foundation trench using standard clean fill dirt and a 15% mechanical compaction buffer.
- length: 30
- width: 10
- depth: 12
- soil_type: 100
- compaction: 15
- volume: 12.78 cu yd
- volume_cuft: 345.0 cu ft
- weight: 17.25 tons
- tandem_trucks: 2
- triaxle_trucks: 1
Frequently Asked Questions
What is fill dirt?
Fill dirt is subsoil excavated from beneath the organic topsoil layer. It consists of inorganic sand, clay, and small gravel rocks. Because it contains no decomposing organic matter, it does not rot, decay, or create subterranean sinkholes, making it ideal for structural grading.
How much does a cubic yard of fill dirt weigh?
A cubic yard of dry fill dirt weighs approximately 2,400 to 2,700 pounds (1.2 to 1.35 tons). Wet clay or damp structural fill can weigh over 3,000 pounds (1.5 tons) per yard.
How many cubic yards are in a dump truck of fill dirt?
A standard single-axle dump truck carries about 5 to 7 cubic yards. A tandem-axle dump truck carries 10 to 12 cubic yards, while a large tri-axle truck carries 14 to 16 cubic yards (approx. 18 to 22 tons).
Why does fill dirt need a compaction buffer?
Loose dirt delivered from a truck fluffs up with air voids. When you grade and tamp the soil, it consolidates and shrinks in volume by 15% to 20%. Adding a compaction buffer ensures your final grade does not sink below desired elevation.
Can I grow grass or plants directly in fill dirt?
No. Fill dirt lacks organic nutrients, microorganisms, and aeration required for root systems. It packs into a dense hardpan layer when dry. Always cap fill dirt with at least 3 to 6 inches of rich topsoil before planting lawn sod or flowers.
What is certified "clean fill"?
Clean fill is inert natural earth that has been screened and certified free of environmental contaminants, chemical toxins, demolition debris, broken glass, metal, and garbage.