Dirt Calculator

About the Dirt Calculator

Whether you are levelling a yard, filling a low spot, building up a garden or backfilling around a new foundation, dirt is ordered by the cubic yard and delivered by the truckload. The amount looks simple to work out, but it is easy to slip between feet and inches, and the delivery fee per load often costs more than the dirt itself. Knowing the number of loads before you call a supplier avoids paying for an extra half-empty truck.

This dirt calculator gives the cubic yards of dirt for an area and depth, its approximate weight, how many dump-truck loads it will take, and the total delivered cost. Choose between fill dirt, screened topsoil and clay fill, which differ in weight and price.

How to Use the Dirt Calculator

Choose the type of dirt.

Enter the length and width in feet and the depth in inches.

Enter the dump truck size in cubic yards, the price per cubic yard and the delivery fee per load.

The Formulas

  cubic yards  = length × width × depth ÷ 324
  tons         = cubic yards × density (fill 1.2, topsoil 1.1, clay 1.4)
  loads        = ⌈cubic yards ÷ truck size⌉
  cost         = cubic yards × price + loads × delivery

Step-by-Step Example

Fill dirt for a 30 × 20 ft area, 6 inches deep, $15 a yard, $100 per 10-yard load.

  volume   30 × 20 × 6 ÷ 324 = 11.11 yd³
  weight   11.11 × 1.2 = 13.33 tons
  loads    ⌈11.11 ÷ 10⌉ = 2 loads
  cost     11.11 × $15 + 2 × $100 = $166.67 + $200 = $366.67

Notice that the second load carries just over one yard. Reducing the depth slightly, or ordering exactly 10 yards and making up the difference from elsewhere, would save a delivery fee.

Types of Dirt

Fill dirt is subsoil dug from below the topsoil layer. It has little organic matter, so it does not rot or shrink much over time once compacted, which makes it the right choice for raising ground, filling holes and backfilling. Screened topsoil is the dark upper layer, sieved to remove stones and roots, used where plants will grow. It costs more and should only be used in the top 4 to 6 inches. Clay fill is dense and holds water, useful for pond banks and for sloping soil away from foundations, but it drains poorly and is heavy to work.

Truck Sizes and Weight

Dump trucks are limited by both volume and weight. A small single-axle truck carries about 5 to 6 cubic yards, a tandem about 10 to 14 and a tri-axle around 16 to 18. Heavy, wet clay can hit the legal weight limit before the box is full, so a truck may carry fewer yards of clay than of topsoil. Ask the supplier how many yards their truck carries of the material you are buying.

Access and Placement

A loaded dump truck weighs 20 to 35 tons, enough to crack driveways, crush septic tanks and leave deep ruts in lawns. Decide where the dirt should be tipped before the truck arrives, on firm ground as close to the work as possible. The driver can often spread a load by tipping while driving forward slowly, which saves a lot of wheelbarrow work if the area is accessible. Mark buried pipes, cables and septic lines so the truck avoids them.

Spreading and Settling

Loose dirt settles as it is walked on, rained on and compacted. For lawns and beds, spread it a little higher than the finished level and let it settle, or compact it lightly with a roller. For raising a grade under a patio or shed, compact it in layers and allow for shrinkage, as worked out by the fill dirt calculator.

Estimating Depth on Uneven Ground

Few yards are perfectly flat, so the depth of dirt needed varies from place to place. A simple way to find an average is to set a string line at the finished height, measure down to the ground at several evenly spaced points, and average the measurements. For larger areas, divide the ground into a grid of squares, find the average depth of each, and add up the volumes. A rotating laser level makes this quick and accurate, and can be rented by the day.

Getting Rid of Dirt

Sometimes the job is the reverse: you have too much dirt. Excess fill can often be given away through local listings to people who need it, or a hauler can take it, usually for a fee per load. Clean fill is easier to dispose of than soil mixed with rubble, roots or concrete, so keep them separate as you dig.

Weather and Timing

Dirt is easiest to handle when it is dry enough to crumble but not dusty. Wet soil is heavy, sticks to tools and wheels, and compacts into hard clods that are difficult to level. Schedule deliveries for a dry spell where you can, and cover the pile with a tarp if rain is due before you spread it.

Understanding Your Result

The headline gives the cubic yards of your chosen dirt.

The volume line shows the working and the weight in tons.

The truckloads line gives the number of dump-truck loads.

The cost line adds the dirt and the delivery fees.

When Should You Use This Calculator?

Use it before calling a supplier to order dirt.

Use it to compare quotes with different truck sizes and delivery fees.

Use it to decide whether fill or topsoil is needed for each part of a job.

Common Mistakes

Forgetting delivery costs. They often exceed the price of the dirt.

Ordering topsoil for fill. Fill dirt is cheaper and compacts better.

Tipping on a septic system. Plan the truck's route.

Ignoring settling. Loose dirt sinks over the first months.