Fill Dirt Calculator: Cubic Yards of Dirt for Any Project

Fill Dirt vs Topsoil: What Is the Difference?

Fill dirt is subsoil dug from below the topsoil layer, and it contains almost no organic matter. It comes from grading cuts, excavation spoil, or dedicated fill pits, and its main job is to hold shape and bear load once compacted. That's why builders use it to raise ground level and back-fill behind retaining walls: it packs down predictably and doesn't decompose or shrink over time the way organic material does.

Topsoil sits on top of the ground and is defined by what fill dirt lacks: organic matter, microbes, and the nutrient content that grows plants. The two materials are not interchangeable. Use fill dirt to build structure below grade, then cap the top 6 inches with real topsoil wherever plants need to grow. Ordering fill dirt when the project actually needs topsoil is one of the most common and costly mistakes in a landscaping quote.

When to Use Fill Dirt

Fill dirt is the right material for 6 common situations:

• Raising a low spot in the yard to redirect surface drainage away from a house or shed.
• Filling behind a new retaining wall, where compacted structural fill keeps the wall from bulging under soil pressure.
• Building a level, load-bearing pad for a shed, patio, or driveway base before adding gravel and pavers.
• Filling around a foundation once formwork or old backfill is removed during a renovation.
• Raising a hardscape area above the surrounding grade so water sheds away instead of pooling.
• Bulk grading on new construction sites, where large volumes of overburden or select fill get moved to set the final elevation before landscaping begins.

Fill Dirt Compaction Factor

Fill dirt loses 10 to 15% of its loose volume once compacted. A loose cubic yard fresh off the truck settles to about 0.85 to 0.9 cubic yards after a plate compactor pass, a roller pass, or roughly six months of rain and foot traffic doing the same job more slowly. This is the opposite direction from the settling gardeners plan for with topsoil: fill dirt is meant to compact tighter, since a loose structural fill layer is a future sinkhole under a patio or driveway. The calculator's order quantity adds 15% to the calculated volume so the finished, compacted grade actually matches the height you designed for. Skipping this allowance is the single most common reason a fill dirt delivery falls short.

Material Density Table

How Many Yards of Dirt Do I Need?

Three worked examples cover most residential fill dirt jobs:

• Small grading job: a 20 × 20 ft area at 6 inches deep needs 20 × 20 × 0.5 = 200 cu ft, or 7.4 cu yd. Order 8.5 cu yd with the 15% compaction allowance.
• Behind a retaining wall: a 40 ft run, 4 ft wide, 4 ft deep needs 40 × 4 × 4 = 640 cu ft, or 23.7 cu yd. Order 27.3 cu yd.
• Pad for a 12 × 16 ft shed: at 8 inches deep needs 12 × 16 × 0.667 = 128 cu ft, or 4.7 cu yd. Order 5.4 cu yd.

For any area larger than a truckload (10 to 14 cu yd), break the site into rectangular sections on a sketch, calculate each one, and sum the totals before calling a supplier.

Fill Dirt Cost Estimate

Bulk fill dirt costs $8 to $25 per cubic yard, depending on local supply and whether it's clean fill, select fill, or clay. Delivery adds $100 to $300 per truckload on top of the material cost, so the price per yard drops sharply as the order size grows. A small 5-yard order can cost as much per yard as a 20-yard order, purely because delivery is a flat charge per trip.

Grading, Drainage, and Retaining Walls

Fill dirt does the structural work in three hardscape situations. For grading, the finished slope should fall at least 2% (a 2-inch drop over 8 feet) away from any building, so surface water runs off instead of pooling against a foundation. For drainage improvements, a layer of sandy loam fill drains faster than clay and reduces standing water after storms. For retaining walls, fill goes in behind the wall in compacted lifts of 6 to 8 inches at a time. Compacting one thick layer instead of several thin ones is the most common cause of a bulging or leaning wall within the first year.

Frequently Asked Questions