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Fill Dirt Calculator: How Much Do You Need?

What Is Fill Dirt?

Fill dirt is subsoil material excavated from below the living layer of earth — typically from depths of 12 to 36 inches where no organic matter, roots, or biological activity remains. This is the crucial distinction between fill dirt and topsoil: fill dirt contains no humus, no decomposing plant matter, no active microbes, and no nutrients that plants can use. That apparent limitation is exactly what makes it valuable for structural applications. Because fill dirt lacks organic content, it does not decompose, settle unpredictably, or create voids under structures over time the way topsoil-based fills would.

The material is most commonly a clay-loam or silty-clay blend from construction excavations — what gets hauled away when a basement is dug, a road is cut, or a building foundation is poured. It is the most abundant bulk fill material in the United States, and in many regions it is available at low or no cost from contractors who need to dispose of excavation spoils. Color ranges from reddish-brown clay to gray silty material depending on local geology; neither color is inherently better than the other for fill purposes.

Fill dirt is heavier than topsoil in its natural state due to higher clay content and lower air space, weighing approximately 80 pounds per cubic foot (1.08 tons per cubic yard). However, the figure that matters most for fill dirt projects is not its density but its compaction rate. When loose fill dirt is placed and then mechanically or naturally compacted, it shrinks 15–25% from its loose volume. A project calling for 8 inches of finished compacted fill requires approximately 10 inches of loose fill dirt to achieve that result.

How to Calculate How Much Fill Dirt You Need

Fill dirt is sold by the cubic yard. The volume calculation is the same as for any bulk material, but you must add the compaction factor before ordering.

Formula: Length (ft) × Width (ft) × Average Depth (ft) = Cubic feet → ÷ 27 = Cubic yards → × 1.20 = Cubic yards with compaction

Worked example — filling a low spot, 25 ft × 15 ft × 8 inches deep at the center:

That extra 20% compensates for the settlement that occurs when the fill is driven over, rained on, and gradually consolidates into the surrounding soil over the first season.

Coverage Table

Depth (loose) Per cubic yard Finished depth after compaction Notes
3 inches 108 sq ft ~2.5 inches Minor grade correction
6 inches 54 sq ft ~5 inches Moderate yard raise
12 inches 27 sq ft ~10 inches Major elevation change
18 inches 18 sq ft ~15 inches Deep fill, foundation area
24 inches 13.5 sq ft ~20 inches Structural fill, retain wall backfill

Add 20% to your cubic yard estimate in all cases to account for compaction loss. If the fill will be placed in thin lifts and mechanically compacted with a plate compactor or sheep’s-foot roller, a 15% factor is sufficient.

How Much for Common Fill Dirt Projects

Filling a low wet spot in a lawn — 30 ft × 20 ft, averaging 6 inches deep

Low spots collect standing water after rain and support moss instead of grass:

Grading a backyard — 60 ft × 40 ft area, average 3 inches of raise needed

Establishing positive drainage away from a foundation often requires raising the grade:

Raised planter mound — 10 ft × 8 ft footprint, 18 inches tall

Freestanding landscape mounds for ornamental plantings require structural fill under the topsoil layer:

Backfill around a new 40 × 30 ft home addition foundation

Excavation spoils are re-graded against foundation walls after waterproofing:

Buying and Delivery Tips

Fill dirt occupies an unusual position in the landscape materials market: it is often the least expensive or even free material available, but delivery logistics make it costly to obtain in small quantities. Many excavating contractors and site graders actively seek locations to dump excess fill dirt from their job sites, and homeowners with significant grading projects sometimes arrange to receive this material at no charge. The trade-off is that you have no control over the quality, composition, or arrival timing when accepting donated fill.

When paying for fill dirt from a landscape supplier, ask whether the material is screened or unscreened. Unscreened fill may contain rocks, buried debris, chunks of concrete, or roots from prior site disturbance — not a problem for deep fill under a future driveway or building pad, but unacceptable for yard grading close to the surface where lawn mowing equipment will eventually operate. Screened fill costs slightly more but is worth the premium for any application where the surface will be planted or maintained.

The single biggest source of under-ordering on fill dirt projects is ignoring compaction. Contractors with field experience consistently add 20–25% over their calculated volume, because fill dirt placed loosely will always shrink. Water and gravity do the work over the first growing season, but mechanical compaction during placement speeds the process and produces a more predictable finished grade. If you are grading near a foundation or under a structure, always compact fill in maximum 6-inch loose lifts rather than placing the full depth at once.

Truck access and soil conditions on the day of delivery matter as much for fill dirt as for any other bulk material. A fully loaded tandem truck carrying 14 cubic yards of fill weighs over 40 tons and will leave deep ruts in soft lawn areas. Ask the driver to drive on an existing driveway or hardscape surface wherever possible, and spread smaller quantities with a wheelbarrow to avoid damaging soft ground.

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Shape
1.85cubic yards
US tons
2.00 tons
Cubic feet
50.00 ft³
Weight
4,000 lb

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Frequently Asked Questions

How big is 10 cubic yards of fill dirt?

Ten cubic yards of fill dirt equals 270 cubic feet. Visualize it as a pile roughly 10 feet wide, 10 feet long, and 3 feet tall — or about the size of a standard dump truck load. Spread at 3 inches deep, 10 yards covers 1,080 square feet. At 6 inches, it fills 540 square feet. At 12 inches, 270 square feet.

How many cubic yards of fill dirt do I need?

Measure the length and width of the area to fill in feet, then measure or estimate the average depth of fill needed. Multiply length × width × depth (in feet) and divide by 27 for cubic yards. Add 15–25% for compaction shrinkage, since loose fill dirt settles significantly once placed. If the area is irregular, break it into rectangular sections and calculate each one separately.

How much fill dirt do I need per square foot?

At 3 inches deep, one square foot requires 0.00926 cubic yards of fill dirt. At 6 inches, that doubles to 0.0185 cubic yards per square foot. Multiply these figures by your total square footage, then add 20% for compaction. For quick planning: at 6 inches of fill, you need roughly 1 yard per 54 square feet before compaction adjustment.

How do I calculate fill dirt with compaction factor?

Once you have your raw volume in cubic yards, multiply by 1.20 (20% compaction factor) for average fill dirt on typical soil, or 1.25 (25%) for sandy or silty material that settles more. For example, a project needing 20 yards of finished fill requires 20 × 1.20 = 24 yards of loose material to order. If the fill will be mechanically compacted with a plate compactor or roller, use 1.15 (15%) instead.

How many tons of fill dirt are in a cubic yard?

Fill dirt weighs roughly 80 pounds per cubic foot, which equals 2,160 pounds per cubic yard — just over 1.08 US tons. Unlike gravel, fill dirt is always sold by the cubic yard rather than by the ton, since its density varies considerably depending on clay content, moisture, and the depth from which it was excavated. Use cubic yard measurements when ordering.

How much does fill dirt cost per yard?

Fill dirt often costs less than any other bulk landscape material because it is a byproduct of construction excavation rather than a quarried product. Pricing ranges from free (many contractors offer to haul it away at no charge if you accept their excavation spoils) to $15–$30 per yard delivered in markets where fill dirt must be trucked significant distances. Delivery charges of $50–$150 per load are common regardless of material cost.

How many truckloads of fill dirt do I need?

A standard tandem-axle dump truck carries 10–14 cubic yards of fill dirt, depending on the truck's capacity and the material's weight. At 12 yards per load, a project needing 60 cubic yards requires 5 truckloads. For large projects, confirm the truck capacity with your supplier before scheduling, as actual volume per load varies by equipment.

How do I calculate fill dirt for a sloped area?

For a sloped area, calculate the average depth of fill by adding the minimum depth at the high end to the maximum depth at the low end and dividing by 2. Multiply that average depth (in feet) by the total area in square feet, then divide by 27 for cubic yards. For complex slopes with multiple grades, divide the area into triangular or trapezoidal sections and calculate each separately.

Last updated: 2026-06-29