Dirt Calculator
Fill dirt sells by the cubic yard, but your project is measured in square feet and depth. This calculator bridges that gap — converting your coverage area into cubic yards, tons, and total cost for grading, backfilling, and leveling projects.
Quick Reference
Fill Dirt Types Compared
Different fill dirt types serve different purposes. Here is a comparison to help you choose the right one for your project:
| Type | Weight (lbs/ft³) | Tons/Yard³ | Best For | Typical Price/yd³ |
|---|---|---|---|---|
| Standard Fill | 100 | 1.35 | General grading, leveling | $8-$15 |
| Clean Fill | 90 | 1.22 | Residential landscaping | $12-$20 |
| Structural Fill | 110 | 1.49 | Foundations, driveways | $15-$30 |
| Clay Fill | 105 | 1.42 | Waterproofing, ponds | $10-$18 |
| Sandy Fill | 95 | 1.28 | Drainage areas, backfill | $10-$20 |
Fill Dirt Depth Guide
Depth depends on your project. Too thin and it won't provide adequate coverage. Too deep without compaction and it will settle unevenly.
| Depth | Best For | Compaction Notes |
|---|---|---|
| 6 inches | Light grading, lawn prep | Single pass with roller |
| 12 inches | Standard grading, general fill | Compact in 6" lifts |
| 18 inches | Foundation backfill | Compact in 6" lifts |
| 24+ inches | Deep fill, berms, raising grade | Compact in 4-6" lifts |
How to Use This Calculator
Step 1: Choose your area shape - Rectangle for standard areas, Circle for tree wells, or Total Area if you already know the square footage.
Step 2: Enter dimensions. For rectangle, enter length and width. For circle, enter diameter. For total area, enter square footage directly.
Step 3: Set depth using the preset buttons (6"-24") or enter a custom value.
Step 4: Select dirt type and enter pricing. The calculator shows material cost plus delivery.
Step 5: Results show instantly - cubic yards, tons, cost breakdown, and total with delivery.
Fill Dirt Formula
The calculator converts your project dimensions into fill dirt volume and cost:
- Rectangle: Area = Length x Width
- Circle: Area = Pi x (Diameter / 2)²
- Volume (ft³) = Area (ft²) x (Depth in inches / 12)
- Volume (yd³) = Volume (ft³) / 27
- Tons = Volume (ft³) x Density (varies by type) / 2,000
- With Compaction = Volume (yd³) x (1 + Compaction Factor / 100)
- Material Cost = Volume with Compaction x Price per Cubic Yard
- Total Cost = Material Cost + Delivery Fee
Density varies by fill dirt type. Structural fill is the densest at 110 lbs/ft³, while clean fill is lighter at 90 lbs/ft³. The dirt type dropdown adjusts the density automatically.
Worked Example: Backfilling a Foundation
Let us calculate fill dirt for a 30 ft x 15 ft area at 18 inches deep using standard fill dirt (100 lb/ft³) with 15% compaction and $75 delivery.
Step 1: Calculate volume:
Volume = 450 x (18 / 12) = 675 ft³
Cubic Yards = 675 / 27 = 25 yd³
Step 2: Add compaction factor:
Step 3: Calculate cost at $12/yd³:
Total = $345 + $75 delivery = $420.00
Cost per yd³ = $420 / 28.75 = $14.61
Total: 28.75 cubic yards of fill dirt at $420.00. Use the calculator above to model your own project.
Tips and Common Mistakes
Best Practices
- Compact in lifts - Never dump more than 6 inches at a time without compacting.
- Order 10-15% extra - Fill dirt compacts and settles; extra covers losses.
- Check drainage - Fill dirt can redirect water flow; plan drainage before filling.
- Verify soil type - Ask your supplier what you are getting; not all fill dirt is equal.
- Have a plan for access - Dump trucks need 12+ feet of clearance and firm ground.
Avoid This
- Dumping deep fills all at once: This causes uneven settling and potential structural issues.
- Ignoring drainage: Fill dirt can redirect water toward your foundation.
- Using fill dirt for growing: Fill dirt has no nutrients and compacts heavily. Use topsoil for plants.
- Not compacting: Uncompacted fill will settle over time, creating dips and uneven surfaces.
- Skipping the soil test: You may need specific fill types for your project conditions.
Frequently Asked Questions
Multiply length x width x depth (all in feet), then divide by 27. For example, a 20x10 ft area at 6 inches deep needs 100 cubic feet = 3.7 cubic yards. Add 10-15% for compaction.
Fill dirt costs $8-$25 per cubic yard in 2026. Subsoil fill runs $8-$15, clean fill costs $12-$20, and structural fill ranges $15-$30 per cubic yard. Delivery adds $50-$150.
Fill dirt is subsoil with no organic matter, used for grading and backfilling. Topsoil is nutrient-rich and used for growing plants. Never use fill dirt for gardens or lawns.
Fill dirt weighs 2,000-2,500 lbs per cubic yard (74-93 lbs per cubic foot). Compacted fill dirt can weigh 2,800-3,600 lbs per cubic yard. Weight varies with moisture and clay content.
For general grading, 6-12 inches is typical. For foundation backfill, 12-24 inches. For building berms or raising grade significantly, 24+ inches. Compact in lifts of a few inches at a time.
Yes, fill dirt should be compacted in lifts (layers of a few inches) to prevent settling. Order 10-15% extra to account for compaction loss. Never dump deep fills all at once.