How to calculate fill dirt
- Measure the area to be filled in feet.
- Find the average fill depth. On sloped or uneven ground, take depth readings across a grid (stakes and a string line or a laser level) and average them.
- Convert to cubic yards: area × depth in inches ÷ 324.
- Add a compaction allowance. Loose fill delivered by truck loses volume when it is compacted, so order 15–25% more than the finished volume.
Dirt formula
Tons = Cubic yards × weight per yard
Worked example: leveling a low corner of the yard
An area 30 ft × 20 ft needs an average of 6 in of fill: 30 × 20 × 6 ÷ 324 = 11.11 cubic yards compacted. Adding 20% for compaction gives 13.33 cubic yards to order — about two loads on a 10-yard truck, or roughly 16.7 tons of moist fill.
Compaction and shrink
Earthwork has three volumes: bank (in the ground), loose (dug up and in the truck) and compacted (spread and rolled). Soil swells when it is dug and shrinks when it is compacted. For ordering fill, the compacted volume you need is what matters, so the calculator adds an allowance to cover the shrink from loose to compacted. 15–25% is a common planning range; sandy soils compact less and clays more.
How much does dirt weigh?
| Material | Tons per cubic yard | Pounds per cubic yard |
|---|---|---|
| Fill dirt, dry | about 1.0–1.1 | 2,000–2,200 |
| Fill dirt, moist | about 1.2–1.3 | 2,400–2,600 |
| Clay or wet soil | about 1.3–1.5 | 2,600–3,000 |
| Screened topsoil | about 1.0–1.1 | 2,000–2,200 |
Common dump trucks carry roughly 10–14 cubic yards; smaller trucks carry 5–6. A full load of wet clay can exceed a truck's legal weight before it is full by volume, so suppliers may send fewer yards per load.
Fill dirt vs topsoil
Fill dirt is subsoil with little organic matter. It compacts and stays put, which makes it right for raising grade, backfilling foundations and trenches, and building up a pad. Topsoil is the dark, organic-rich layer that plants grow in, but it settles and breaks down, so it is a poor structural fill. A typical approach is fill dirt to within a few inches of finished grade, then 4–6 in of topsoil on top for lawn or garden.
Grading tips
- Place and compact fill in lifts of about 4–8 in rather than all at once.
- Slope finished grade away from the house — building codes commonly call for a fall of at least 6 in within the first 10 ft.
- Ask for clean fill, free of trash, roots, large rocks and construction debris.
- Call 811 before digging or regrading, and check whether your town requires a grading permit for larger fills.
Frequently asked questions
How much fill dirt do I need?
Multiply length × width in feet by the fill depth in inches and divide by 324 for cubic yards, then add 15–25% for compaction. A 30 × 20 ft area 6 in deep needs about 13.3 cubic yards with a 20% allowance.
How much does a yard of fill dirt weigh?
About 1.0–1.3 tons (2,000–2,600 lb) per cubic yard, depending on moisture and soil type. Wet clay can weigh 1.5 tons or more.
How many yards of dirt are in a dump truck?
Most standard dump trucks carry 10–14 cubic yards; small single-axle trucks carry about 5–6 yards. Weight limits can reduce this for heavy, wet soil.
Why do I need extra fill for compaction?
Loose soil contains air. When it is spread and compacted, its volume drops — typically 15–25% — so you need more loose dirt than the finished space.
Can I use topsoil as fill?
Not for structural fill. Topsoil is organic and keeps settling as it decomposes. Use fill dirt for bulk, then cap it with topsoil where you want plants to grow.
Sources & standards
This calculator's formulas and default values are based on the following codes, standards and published data. Codes are adopted and amended locally, so check with your building department for permitted work. See how we build and check our calculators.
- International Residential Code (IRC) R401.3: drainage and lot grading (6 in fall within 10 ft of the foundation).
- USDA NRCS soil survey guidance on soil bulk density and texture.
- Earthwork industry swell and shrinkage factors for common soils (planning ranges; site soils vary).