Calculate cubic yards, tons and dump-truck loads of fill dirt to raise grade, fill low spots or build up an area, with compaction included.
Fill dirt is ordered by the cubic yard, and the key number most people miss is compaction. Loose fill from a truck takes up more space than the same dirt after it's been compacted in place. Order only the "math" volume and you'll come up short, often by 15–25%.
Cubic Yards = (Length × Width × Depth in inches ÷ 12) ÷ 27 × Compaction Factor(30 × 20 × 0.5) ÷ 27 × 1.20 = 13.3 cubic yards
If the depth varies across the area, as it does when you fill a slope, take depth readings in several spots and use the average. For a wedge that tapers from 12 inches to zero, use half the maximum depth.
Fill dirt is subsoil. It's mostly clay, sand and rock with little organic matter, which is exactly why it's used for structural fill: it doesn't decompose and settle over time. It's a poor growing medium, though. If the area will be lawn or planting beds, bring it up with fill, then finish with 4–6 inches of topsoil. Our topsoil vs. fill dirt guide covers the differences in detail.
| Situation | Add for Compaction |
|---|---|
| Light fill, hand-raked (garden beds) | 10% |
| Typical yard grading, lightly rolled | 15–20% |
| Structural fill compacted in lifts | 20–25% |
For anything that will carry weight, like a shed pad, patio subgrade or driveway, spread fill in 4–6 inch lifts and compact each lift before adding the next. Dumping 2 feet of loose fill and compacting only the top leaves soft dirt underneath that will settle for years.
Fill is most often used to fix drainage. The usual target, found in many residential building codes, is ground that falls at least 6 inches within the first 10 feet from the foundation. Keep fill below siding and weep holes, and never bury the bottom of wood framing. Call 811 before you regrade so buried utility lines are marked.
| Item | Typical Cost |
|---|---|
| Fill dirt (material only) | $5–$20 per cubic yard |
| Screened fill | $12–$30 per cubic yard |
| Delivery, single truckload | $150–$600 per load |
| Spreading & compaction (contractor) | $1–$3 per sq ft |
Delivery is often the biggest part of the bill, so a full truckload can cost little more than half of one. A tandem dump truck typically carries 10–14 cubic yards, and a single-axle truck carries 5–7. Contractors sometimes give fill away free from excavation jobs. Just make sure it's clean and free of debris.