Quick Answer: To calculate fill dirt, multiply Length (ft) x Width (ft) x Depth (in) / 12 / 27 to get cubic yards, then multiply by 1.125 for compaction. Clean fill dirt weighs about 2,000 lbs/cu yd. One cubic yard covers 54 sq ft at 6 inches deep. Add 10% for waste. For a 20 x 15 ft area at 6 inches deep, you need approximately 6.17 cubic yards pre-compaction (6.94 cu yd post-compaction), weighing about 13,889 lbs, at an estimated cost of $104 at $15/cu yd.
Calculate how much fill dirt you need for grading, leveling, backfill, or foundation work. Enter your dimensions, choose your fill type, and get the exact amount in cubic yards (with compaction factor), total weight, number of bags, and estimated cost.
How to Calculate Fill Dirt
The formula for calculating fill dirt volume accounts for both the raw volume and the compaction that occurs after placement:
- Measure the length and width of the area you need to fill in feet.
- Determine the fill depth. Use 4-6 inches for minor grading, 6-12 inches for significant leveling, or the full trench depth for backfill projects.
- Multiply length × width to get the area in square feet.
- Multiply the area by the depth (converted to feet) to get the volume in cubic feet.
- Divide by 27 to convert to cubic yards (the standard bulk purchasing unit).
- Multiply by 1.125 to account for compaction. Fill dirt compresses 10-15% when tamped, so you need to order more loose material than the space you are filling.
- Add 10% for waste from spillage, uneven subgrades, and delivery loss.
Fill Dirt Coverage Chart
Quick reference for how much area one cubic yard of fill dirt covers at different depths (before compaction):
| Depth | Coverage per Cubic Yard | Weight (Clean Fill) |
|---|---|---|
| 2 inches | 162 sq ft | 2,000 lbs |
| 4 inches | 81 sq ft | 2,000 lbs |
| 6 inches | 54 sq ft | 2,000 lbs |
| 8 inches | 40.5 sq ft | 2,000 lbs |
| 12 inches | 27 sq ft | 2,000 lbs |
Types of Fill Dirt
- Clean Fill Dirt: The most common and affordable type. Clean fill is natural subsoil free of organic material, debris, and contaminants. It weighs approximately 2,000 lbs per cubic yard and is ideal for general grading, leveling low spots, and raising the elevation of a yard. Because it contains no organic matter, it will not decompose or settle over time.
- Structural Fill: An engineered blend of soil and aggregate (gravel or crushed stone) designed to bear heavy loads. At roughly 2,400 lbs per cubic yard, it is denser and more expensive than clean fill. Use structural fill for building pads, retaining wall backfill, and anywhere that will support a structure or heavy traffic.
- Screened Fill: Clean fill that has been run through a screening machine to remove rocks, roots, and large clumps. At about 2,200 lbs per cubic yard, it provides a smoother, more uniform product that is easier to grade and compact. It costs more than unscreened clean fill but saves labor on-site.
- Clay Fill: Soil with a high clay content that weighs around 2,600 lbs per cubic yard. Clay fill is excellent for creating impermeable barriers, such as pond bottoms or drainage diversion. However, it expands and contracts with moisture changes, so avoid using it near foundations or in areas where drainage is critical.
Understanding Compaction
When fill dirt is dumped from a truck, it is in a loose, uncompacted state with air pockets between the particles. As the dirt is spread and tamped, these air pockets collapse, reducing the overall volume by 10-15%. This is called the compaction factor, and it means you must order more loose dirt than the volume of the space you are filling.
Our calculator uses a 12.5% compaction factor (multiply by 1.125), which represents the midpoint of the typical 10-15% range. Sandy soils sit closer to 10% compaction, while clay-heavy soils compact closer to 15%. Proper compaction is essential for preventing future settling, especially under driveways, foundations, and hardscaped areas.
For best results, compact fill dirt in lifts (layers) of 6-8 inches. Spread a layer, compact it with a plate compactor or hand tamper, then add the next layer. This ensures uniform density throughout the fill area and prevents uneven settling months or years down the road.
Common Applications for Fill Dirt
- Yard Grading and Leveling: Use 4-8 inches of clean fill to correct drainage issues, eliminate low spots, and create a smooth, even surface for sod or seed. Always grade away from the foundation at a minimum slope of 1 inch per foot for the first 6 feet to prevent water pooling near the house.
- Foundation Backfill: After pouring a foundation or installing footings, the trench around the perimeter needs to be backfilled with compacted fill dirt. Use structural fill for this application to prevent settling and ensure proper load transfer. Compact in 6-inch lifts.
- Raising Grade for New Construction: Building pads for sheds, garages, and additions often require raising the existing grade by 12-24 inches. Structural fill provides the load-bearing capacity needed, and proper compaction prevents differential settlement under the new structure.
- Slope and Erosion Repair: Fill dirt can rebuild eroded slopes, fill washouts, and create terraced areas. For slopes, compact the fill in horizontal lifts rather than placing it all at once. Consider using clay fill for its binding properties on steep slopes where erosion is a concern.
- Septic System and Utility Backfill: After installing septic tanks, drain lines, or underground utilities, the trenches must be carefully backfilled. Use clean fill (never clay, which can expand and damage pipes) and compact gently to avoid shifting or damaging the installed systems.
Tips for Ordering Fill Dirt
- Always order 10-15% extra beyond your calculated amount. Between compaction, spillage during delivery, uneven subgrade, and spreading losses, you will use more than the pure mathematical volume.
- Check local regulations before ordering. Some municipalities require fill dirt to be certified clean (free of contaminants). Ask your supplier for a soil test report if you are using fill near a well, garden, or waterway.
- Coordinate delivery access. A standard dump truck carries 10-14 cubic yards and needs a firm, level surface to dump. Identify where the truck will drop the load and plan a path for wheelbarrows or a skid steer to distribute the material.
- Order by the truckload for large projects. Bulk fill dirt is dramatically cheaper than bagged. A full truckload of 10 cubic yards might cost $150-300, while the same volume in 50 lb bags from a home improvement store could run $800-1,200.
- Ask about free fill dirt. Construction sites, excavation contractors, and pool installers often have clean fill dirt they need to dispose of. Check local classifieds, Facebook Marketplace, or apps like DirtMatch. You may only pay for delivery.
- Do not use fill dirt for planting. Fill dirt contains no organic matter or nutrients. If you plan to grow grass, plants, or a garden on top, add 4-6 inches of quality topsoil over the compacted fill as a final layer.
Formula Summary
Fill Dirt Volume Formula: To calculate the cubic yardage of fill dirt needed, multiply the Length (ft) x Width (ft) x Depth (in), divide by 12 to convert depth to feet, then divide by 27 to convert cubic feet to cubic yards.
V(cu yd) = (L(ft) x W(ft) x D(in)) / (12 x 27)
Compaction Formula: Fill dirt compacts 10-15% when tamped. Multiply the base volume by 1.125 (12.5% compaction factor) to determine how much loose fill dirt to order.
Order Volume = V(cu yd) x (1 + Waste%) x 1.125
Circular Area: A = pi x (d / 2)^2 where d is the diameter in feet.
Weight Formula: W(lbs) = Order Volume(cu yd) x density where density is the fill dirt density in lbs/cu yd.
Bag Count: Bags(50 lb) = ceil(W(lbs) / 50)
| Fill Dirt Type | Density (lbs/cu yd) |
|---|---|
| Clean Fill Dirt | 2,000 |
| Structural Fill | 2,400 |
| Screened Fill | 2,200 |
| Clay Fill | 2,600 |
Standard Assumptions: Compaction factor of 12.5% (multiply volume by 1.125). Waste factor of 10% accounts for spillage and uneven subgrades. 1 cubic yard = 27 cubic feet. Standard bag size is 50 lbs. 1 ton = 2,000 lbs.
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Estimates are for planning purposes only. Consult a qualified contractor for critical projects. Actual material requirements may vary based on site conditions, waste, and installation methods.
Pricing last verified: February 2026. Material prices vary by region, season, and supplier. Prices shown are national averages for planning purposes.