When purchasing bulk landscaping materials like topsoil, the term “yard” refers to a measure of volume known as a cubic yard, not a linear distance. This is how suppliers quantify the three-dimensional space the material occupies. A cubic yard is equivalent to 27 cubic feet and represents a standardized quantity for transporting and selling large amounts of loose material. Understanding this measure is the first step in accurately planning any project involving adding soil.
Defining the Standard Cubic Yard
The cubic yard is defined by a 3x3x3 foot cube, containing 27 cubic feet of material. This serves as the universal benchmark for ordering topsoil in bulk. A single cubic yard roughly fills the bed of a standard-sized pickup truck or is equivalent to about 27 one-cubic-foot bags of soil.
Translating this volume into a practical coverage area depends entirely on the depth of the layer applied. Since the total volume is fixed at 27 cubic feet, spreading the material thinner covers a much larger area. For instance, one cubic yard of topsoil covers 324 square feet if spread only one inch deep.
Increasing the depth significantly reduces the covered area, which is an important consideration for common projects like preparing a new lawn or filling a raised bed. A three-inch layer requires one cubic yard to cover 108 square feet. For a deeper, six-inch application, the same volume will cover 54 square feet.
How Soil Density Affects the Weight
Although topsoil is purchased by volume in cubic yards, the material is handled and delivered according to its weight, which depends on its density. The weight of a single cubic yard is influenced by two primary factors: moisture content and composition. A cubic yard of dry topsoil can weigh around 1,800 to 2,000 pounds, but if saturated with water, the weight can increase dramatically to between 2,700 and 3,000 pounds.
Water is dense and fills the pore spaces between soil particles, substantially increasing the overall mass. Beyond moisture, the type of material in the topsoil mix also influences its weight. Soil with a high clay content tends to be heavier because particles pack tightly, leaving less air space compared to lighter, more porous soil rich in organic matter or sand. This weight variability has practical implications for delivery and transportation, as trucks have strict load limits.
Calculating the Total Soil Needed for Your Project
Determining the exact amount of topsoil needed requires converting the area dimensions into cubic yard volume. The calculation involves multiplying the length, width, and depth of the project area, all measured in feet. Then, divide the resulting cubic feet by 27. This process ensures efficient ordering, avoiding shortages or excessive waste.
A common challenge is that topsoil depth is often measured in inches, which must be converted into a decimal fraction of a foot before calculation. To convert inches to feet, divide the required depth in inches by 12. For example, a depth of four inches converts to approximately 0.33 feet (4 รท 12).
For a raised garden bed measuring four feet by eight feet with a required depth of 12 inches, the calculation is 4 feet (length) multiplied by 8 feet (width) multiplied by 1 foot (depth), equaling 32 cubic feet. Dividing 32 cubic feet by 27 results in a requirement of about 1.18 cubic yards.