Introduction
Figuring out how much dirt you need to dig out of the ground is one of the first steps in any construction project. Whether you are digging a foundation, a trench, or a pond, you need to know the exact volume of soil to remove. Our Excavation Calculator does this math for you in seconds. Just enter your dimensions, pick your excavation shape, and choose your soil type. The tool gives you three key volume numbers: bank volume (the dirt still in the ground), loose volume (how much space that dirt takes up after you dig it out), and compacted volume (how much it shrinks when packed back down).
Soil swells when you remove it from the ground. Clay can expand by 30%, and blasted rock can grow by as much as 50%. This means the pile of dirt on your truck is always bigger than the hole you dug. Our calculator accounts for this swell factor automatically based on the soil type you select. It also figures out compaction, which matters when you need to backfill or haul material to another site. You can choose from rectangular, trapezoidal, or circular excavation shapes, and even handle sloped or uneven depths where one end of the dig is deeper than the other.
Beyond volume, this calculator estimates how many truck loads you will need and what the total cost will be. Enter your truck capacity, cost per cubic yard or cubic meter, and hauling cost per load. The tool adds it all up so you can plan your budget before the first shovel hits the ground. You can switch between imperial and metric units at any time, and all your numbers convert instantly. Use the built-in soil reference table to compare swell and compaction factors across common soil types like clay, sand, gravel, rock, and topsoil.
How to Use Our Excavation Calculator
Enter the shape and size of your dig area, choose your soil type, and this calculator will give you the bank, loose, and compacted volumes along with truck load estimates and total project costs.
Unit System: Pick either Imperial (feet and inches) or Metric (meters and centimeters) to match how you measure your job site.
Excavation Shape: Select the shape of your dig — Rectangular for standard trenches and foundations, Trapezoidal for sloped-wall excavations, or Circular for round holes like piers and wells.
Sloped / Uneven Depth: Turn this on if the ground is not level. When enabled, you enter a depth at the start and a depth at the end, and the calculator averages them for you.
Length: Enter the total length of the excavation area. For rectangular shapes, this is the longer side of the dig. For trapezoidal shapes, you enter both a top length and a bottom length.
Width: Enter the total width of the excavation area. For trapezoidal shapes, you enter both a top width and a bottom width to account for the angled walls.
Diameter: If you chose a circular shape, enter the full diameter of the round excavation instead of length and width.
Depth: Enter how deep you plan to dig. If you turned on the sloped depth option, enter the depth at the start point and the depth at the end point separately.
Soil Type: Choose the type of soil you are digging through — Clay, Sand, Gravel, Rock, Topsoil, Mixed, or Custom. Each soil type automatically sets a swell factor and compaction factor based on standard earthwork values.
Swell Factor (%): This is the percentage that soil expands after you dig it out of the ground. It updates automatically when you pick a soil type, or you can type in a custom number.
Compaction Factor (%): This is the percentage of the original bank volume that the soil shrinks to when it is compacted back down. It also updates with the soil type or can be set manually.
Truck Capacity: Enter the volume each haul truck can carry per load. A common dump truck holds about 10 cubic yards. The calculator uses this with the loose volume to figure out how many truck loads you need.
Cost per Cubic Yard (or Cubic Meter): Enter the price you pay for each unit of volume excavated. This is multiplied by the loose volume to give you the volume-based cost.
Cost per Truck Load: Enter the flat rate you pay for each truck load hauled off site. This is multiplied by the number of truck loads to give you the trucking cost, which is then added to the volume cost for a total estimated project cost.
What Is Excavation and How Do You Calculate It?
Excavation is the process of digging and removing soil or rock from the ground to create a hole, trench, or open space. It is one of the first steps in most construction projects, including building foundations, swimming pools, basements, utility trenches, and road work. Knowing how much dirt you need to remove — and how much it will cost — is essential for planning any excavation job correctly.
How Excavation Volume Is Calculated
The volume of an excavation depends on its shape and dimensions. For a rectangular dig, you multiply the length × width × depth. For a circular excavation (like a well or pier hole), the formula uses π × radius² × depth. A trapezoidal shape, which is common when sides are sloped, uses a prismoidal formula that accounts for different top and bottom measurements. If the ground is uneven and the depth changes from one end to the other, you use the average of the two depths to get an accurate result. If you need help determining the area of your dig site before calculating volume, our Square Footage Calculator can help with that first step.
Understanding Bank, Loose, and Compacted Volume
One of the most important things to understand about excavation is that soil changes volume when you dig it up. There are three types of volume you need to know:
- Bank (In-Place) Volume: This is the volume of soil while it is still in the ground, undisturbed. It is the starting point for all calculations.
- Loose (Swelled) Volume: When you dig soil out of the ground, it breaks apart and takes up more space. This increase is called the swell factor. For example, topsoil swells about 25%, meaning 1 cubic yard in the ground becomes 1.25 cubic yards in the truck. Clay swells about 30%, and rock can swell up to 50%.
- Compacted Volume: If you put soil back and pack it down with equipment, it shrinks to less than its original bank volume. The compaction factor tells you what percentage of the original volume remains after compaction. For most soils, this is between 80% and 95%.
Loose volume is the number that matters most for hauling, because it determines how many truck loads you need. Compacted volume matters when you are backfilling or building up an area with fill dirt. If you are working with fill material specifically, our Dirt Calculator can help you estimate how much fill dirt you need to bring in for your project.
Soil Types and Their Swell Factors
Different soil types behave differently when excavated. Sand and gravel have low swell factors (12%–15%) because their particles are already loose. Clay swells more (around 30%) because it is dense and clumpy. Blasted rock has the highest swell factor (up to 50%) since solid rock breaks into many irregular pieces that take up much more space. Choosing the correct soil type ensures your volume and cost estimates are accurate. If your project involves working with specific materials like sand or gravel after excavation, you can use our Sand Calculator, Gravel Calculator, or Topsoil Calculator to estimate exact quantities for backfilling or landscaping.
Estimating Truck Loads and Costs
Once you know the loose volume, you can figure out how many truck loads you need by dividing the loose volume by the truck's capacity. A standard dump truck holds about 10 cubic yards. The calculator also estimates costs in two parts: a volume cost (price per cubic yard of material handled) and a trucking cost (price per load for hauling). Adding these together gives you a solid ballpark for your total excavation expense.
Why Accurate Excavation Estimates Matter
Underestimating excavation volume leads to budget overruns, extra truck trips, and project delays. Overestimating wastes money on equipment and hauling you don't need. By entering your exact dimensions, choosing the right soil type, and accounting for swell, you can plan your project with confidence — whether you are a homeowner digging a small trench or a contractor bidding on a large commercial job. Once excavation is complete, you will likely move on to other phases of construction. Our Concrete Calculator can help you figure out how much concrete you need for foundations and footings, while the Rebar Calculator ensures you order the right amount of reinforcement. For projects involving retaining walls around excavated areas, check out our Retaining Wall Calculator. And if your excavation involves pipe trenches, the Pipe Volume Calculator can help you determine pipe capacity and trench requirements.