Dirt Calculator

How to Calculate Dirt or Fill Needed?

Multiply the area length by the width for square footage. Multiply by the depth in feet. Divide by 27 for cubic yards. A grading project 20 x 15 feet at 6 inches deep needs 20 x 15 x 0.5 = 150 cubic feet = 5.56 cubic yards. Fill dirt weighs approximately 2,200-2,400 pounds per cubic yard depending on moisture content and soil composition, so 5.56 yards weighs roughly 12,200-13,300 lbs or about 6.2 tons. The calculator above converts your area and depth into cubic yards and tons for straightforward ordering.

What Types of Dirt Are Used in Construction?

Fill dirt is subsoil with no organic matter, used for grading, raising elevation, backfilling foundations, and filling holes. It compacts well and does not decompose or settle over time, making it the preferred material for structural fill beneath buildings, driveways, and hardscape. Topsoil is the organic-rich upper layer of earth, used for lawns, gardens, and planting areas. Clean fill is dirt certified free of contaminants and debris, often required for projects near waterways or environmentally sensitive areas. Structural fill (often called engineered fill) meets specific compaction and bearing capacity standards for use under foundations and roads. Each type serves a different purpose, and using the wrong one causes problems.

How Much Does Fill Dirt Cost?

Fill dirt is one of the cheapest bulk construction materials. Clean fill costs $5-$15 per cubic yard from a landscape supply yard. Screened fill (with rocks and debris removed) costs $10-$25 per cubic yard. Compactable structural fill runs $15-$30 per cubic yard. Delivery adds $50-$150 per truckload. In some areas, contractors and excavation companies give away clean fill dirt from job sites where they need to dispose of excavated material. Check local classifieds and construction forums for free fill dirt offers. Verify the source to ensure the dirt is clean and free of construction debris, chemicals, and contaminants before accepting free fill.

How Much Does Dirt Weigh?

Dry fill dirt weighs approximately 2,000-2,200 lbs per cubic yard. Moist fill dirt weighs 2,200-2,600 lbs. Wet, saturated dirt can exceed 3,000 lbs per cubic yard. Topsoil (with organic matter) weighs 2,000-2,400 lbs. Clay soil is on the heavier end at 2,400-2,800 lbs. Sandy soil is lighter at 2,000-2,200 lbs. Weight matters for delivery truck loading, structural calculations when filling over culverts or retaining structures, and estimating the number of wheelbarrow or skid steer loads needed to move and spread the material on-site.

When Do You Need Fill Dirt?

Foundation backfill: after pouring a foundation, the excavated area around the walls is backfilled with dirt to restore the original grade. Grading and leveling: correcting uneven terrain, filling low spots in yards, and establishing positive drainage away from buildings. Raising elevation: building up a site before construction to meet flood plain requirements or to create level building pads on sloped lots. Filling holes: abandoned pools, old basements, septic tank removal sites, and utility trench backfill. Landscaping berms: creating raised earth mounds for privacy screening, noise reduction, and aesthetic landform design.

How to Compact Fill Dirt Properly?

Fill dirt must be compacted in lifts (layers) no thicker than 6-8 inches at a time. Spread each lift evenly, moisten to near optimum moisture content (damp but not muddy), and compact with a plate compactor or vibratory roller. Make at least 3-4 passes over the entire area with the compactor. Test the compaction by walking on the surface. If your footprint sinks more than 1/4 inch, more compaction is needed. For structural fill under buildings and pavement, a geotechnical engineer may require Proctor density testing to verify that the fill achieves 95% or greater compaction relative to the laboratory maximum density.

Fill Dirt vs Topsoil: Choosing the Right Material

Use fill dirt when the purpose is structural: raising grade, backfilling, and creating a stable base. Fill dirt compacts firmly, does not decompose, and does not settle over time. Use topsoil when the purpose is growing: lawns, gardens, flower beds, and any area where plants need to root. Topsoil contains organic matter that decomposes slowly, making it unsuitable as structural fill because it settles and compresses as the organic content breaks down. A common layering approach uses fill dirt to build up grade and topsoil as the final 4-6 inches for planting. This combination provides structural stability below and fertile growing conditions on top.

How Many Dump Truck Loads Do I Need?

A standard tandem-axle dump truck holds 10-14 cubic yards. A single-axle truck holds 5-8 cubic yards. A triaxle truck holds 14-18 cubic yards. For a 10-cubic-yard project, one full tandem truck makes a single delivery. For 30 cubic yards, expect 2-3 loads. When ordering, specify whether you need the truck to dump in one spot or spread the dirt across the site. Some trucks have tailgate spreaders that distribute material evenly as they drive forward. For precise grading work, a skid steer or small dozer on-site is essential for final shaping and compaction after the truck dumps the material.

Frequently asked questions