Topsoil is a fundamental material for successful landscaping and gardening, providing the organic matter and nutrients necessary for plants to thrive. Suppliers measure topsoil in cubic yards (volume), but projects require coverage in square feet (area). Understanding this conversion is essential for accurately determining how much material to purchase. The total area a cubic yard covers depends entirely on the intended depth of the application.
Understanding the Cubic Yard
Suppliers sell topsoil in bulk by the cubic yard, a unit of volume representing three-dimensional space. A cubic yard is defined as a cube measuring three feet long, three feet wide, and three feet high. This means that one cubic yard contains 27 cubic feet of material. To help visualize this amount, a single cubic yard is roughly equivalent to the volume of a standard washing machine. This 27 cubic feet figure is the numerical foundation required for all subsequent coverage calculations.
Calculating Coverage Area Based on Depth
The key to calculating the square footage a cubic yard covers is incorporating the desired depth into the volume formula. Since soil depth is often measured in inches, the first step is converting that depth into feet. For example, four inches is converted to feet by dividing it by 12, resulting in 0.33 feet. The core calculation is 27 cubic feet divided by the depth in feet, which equals the coverage area in square feet. A simplified method uses the constant 324 (27 multiplied by 12) divided by the depth in inches to find the square footage coverage per cubic yard.
Common Coverage Examples
Applying the formula provides quick reference numbers for common landscaping and gardening applications. For a light top-dressing on an existing lawn, one inch of topsoil covers 324 square feet per cubic yard. Doubling the depth to two inches, often used for basic lawn leveling, reduces the coverage area to 162 square feet. New garden beds or vegetable patches often require a depth of three inches for healthy root establishment, covering 108 square feet. For deeper applications, such as filling a raised garden bed, a six-inch depth covers 54 square feet per cubic yard.
Factors Affecting Final Coverage
Theoretical coverage calculations assume a perfect, evenly spread layer, but real-world variables cause the actual coverage to differ. The most significant factor is compaction, as loose topsoil settles after being spread and watered. The moisture content of the material also influences the volume, since wet soil is heavier and denser than dry soil. Furthermore, the material type, such as loamy versus sandier topsoil, affects the final density and settling. Because of these unavoidable physical properties, it is recommended to order an extra five to ten percent of topsoil beyond the calculated amount.