Dirt Calculator

How It Works

The calculator turns your depth into feet, multiplies the three dimensions to get cubic feet, and divides by 27, the number of cubic feet in a cubic yard. It then multiplies cubic yards by the weight you picked to get tons.

The weights come from soil bulk density, which is the dry weight of soil in a given volume. An Oklahoma Cooperative Extension fact sheet reports a sampling study from 47 fields, with an average of 1.45 grams per cubic centimeter, and a range of 1.23 to 1.67. Converted with NIST units, those work out to about 1.22, 1.04, and 1.41 tons per cubic yard. The study sampled field soil, not delivered dirt, so treat the result as an estimate.

See Methods and Sources

Worked Example

Here is the math for a low area that is 20 feet long, 10 feet wide, and 6 inches deep, at 1.22 tons per cubic yard.

1. 20 ft x 10 ft = 200 sq ft
2. 6 in / 12 = 0.5 ft
3. 200 sq ft x 0.5 ft = 100 cu ft
4. 100 cu ft / 27 = 3.70 cu yd
5. 100 cu ft / 27 x 1.22 = 4.52 tons

Cubic Yards of Dirt by Area and Depth

Use this table for a quick check before you enter your own numbers.

Tons of Dry Dirt by Area and Depth

These figures use 1.22 tons per cubic yard. Those are dry figures, so they leave out any water in the soil.

Why Dirt Weight Varies

No single weight fits all dirt, because soil changes from one site to the next.

The Oklahoma fact sheet says soil moisture, clay type, and organic matter can all change bulk density. Compaction raises it, since a compacted soil has a higher bulk density than a similar textured uncompacted soil. Organic matter lowers it, because those particles are less dense than soil minerals.

Bulk density is based on dry weight, so these tons leave out any water in the soil. Do not use these tons to judge a truck or trailer load. Ask your supplier what a load of their dirt weighs.

Settling After You Fill

Soil that is loosened or moved can settle over time. The Oklahoma fact sheet notes that tillage can lower bulk density for a while, and that settling and compaction can raise it again later. The result is the space to fill, not always the amount to order. A Wisconsin report gives typical soil expansion values of 10 to 35 percent, depending on soil type, so ask your supplier how much to order for your finished depth, and keep some soil on hand to top it off.

Frequently Asked Questions

These cover the questions that come up most often.