Fill Dirt Calculator: Free Online Fill Dirt Volume Estimator
Use our free fill dirt calculator to determine exactly how much fill dirt you need, including the compaction factor for your construction, grading, or backfill project. Designed for excavation contractors, site preparation crews, and landscapers, this tool calculates both the loose and compacted volume of fill dirt required. Enter your length, width, depth, and compaction factor to get instant, accurate results for ordering.
How to use this calculator.
- Measure the area to be filled. Measure the length and width of the area in feet. For irregular areas, break into rectangles and calculate each section separately.
- Determine the fill depth. Measure or estimate the depth of fill needed in inches. For grading a yard, measure the difference between the current low point and the desired finished grade.
- Set the compaction factor. A value of 1.2 means you need 20% more loose fill than the compacted volume. Sandy soils use 1.1-1.15; clay soils use 1.2-1.3. The fill will settle and compact after placement.
- Review your results. The calculator shows the loose volume (what you order) and the compacted volume (what remains after compaction). Always order based on the loose volume.
How do you calculate fill dirt volume with compaction?
Fill dirt volume accounts for compaction -- loose fill takes up more space than the same material after it is compacted.
Loose Volume (cu yd) = Length (ft) × Width (ft) × Depth (in) ÷ 324
Compacted Volume (cu yd) = Loose Volume (cu yd) × Compaction Factor
Where:
- Loose volume is what you order from the supplier -- the material in its loose, as-delivered state.
- Compacted volume is the material after placement, watering, and mechanical compaction.
- Compaction factor of 1.2 means you lose about 17% of the loose volume to compaction (1 ÷ 1.2 = 0.83).
Example calculation.
Let's calculate the fill dirt needed for a yard grading project.
Scenario: You are filling a low area that is 40 ft long and 25 ft wide with 8 inches of fill dirt. The soil is clay with a compaction factor of 1.25.
- Calculate loose volume: 40 ft × 25 ft × 8 in ÷ 324 = 24.69 cu yd
- Calculate compacted volume: 24.69 cu yd × 1.25 = 30.86 cu yd (amount to order)
Result: You need to order approximately 31 cubic yards of loose fill dirt. After compaction, this will yield approximately 25 cubic yards of compacted fill. At $15-$25 per yard delivered, the material cost is $465-$775.
Tips from the field.
- Compact in lifts. Place fill dirt in 6-8 inch lifts and compact each lift before placing the next. Compacting more than 8 inches at once leaves the bottom of the lift uncompacted, leading to future settlement and low spots.
- Use the right fill material. Clean fill (free of organic matter, debris, and large rocks) is essential. Organic material decomposes over time, causing settlement. Never use topsoil as structural fill -- it contains too much organic matter.
- Water as you compact. Slightly moist soil compacts better than dry soil. Lightly water each lift before compaction. However, saturated soil cannot be compacted -- wait for it to drain if too wet.
- Test compaction. For structural fills (under slabs, footings, or driveways), use a nuclear density gauge or drive a steel probe to verify compaction. The probe should penetrate no more than 1-2 inches with moderate effort in properly compacted fill.
Disclaimer: This calculator provides estimates for planning purposes only. Actual fill requirements vary based on in-situ soil conditions, compaction equipment, moisture content, and material type. For structural fills, consult a geotechnical engineer for compaction specifications. PavementCalculator.com assumes no liability for material overages or shortages.
Cost, price, and density figures on this page reflect approximate U.S. averages as of August 2026 and vary by region, supplier, and material availability.
Frequently asked questions.
What compaction factor should I use for fill dirt?
A typical compaction factor for fill dirt is 1.2 (20% extra) to account for settling and compaction. Sandy soils compact less (1.1-1.15), while clay soils require more (1.2-1.3). Always over-order by 10-20% to ensure you have enough material after compaction.
How much fill dirt do I need for a 50 ft by 30 ft area?
For a 50 ft by 30 ft area with 6 inches of fill, you need approximately 27.8 cubic yards of loose fill. After applying a 1.2 compaction factor, you would need about 33.3 cubic yards of compacted fill, so order approximately 34 cubic yards.
What's the difference between fill dirt and topsoil?
Fill dirt is the subsoil layer beneath topsoil: it contains little to no organic matter, making it stable and less prone to settling. Topsoil is the nutrient-rich upper layer (2-8 inches) used for planting. Use fill dirt for grading and structural support; use topsoil for gardens and lawns.
How much does fill dirt cost?
Fill dirt costs $10-$25 per cubic yard delivered. Clean fill (no debris): $15-$25/yd³. Screened topsoil: $20-$35/yd³. Delivery fees add $50-$100. Most suppliers require minimum 5-10 yard orders. Use our calculator to estimate how many yards you need.
What is the difference between fill dirt and topsoil?
Fill dirt is subsoil: low organic content, used for filling holes and raising grade. Topsoil is nutrient-rich surface soil used for planting. Fill dirt compacts better for structural purposes. Never use topsoil as structural fill.