When purchasing landscaping materials in bulk, such as wood bark or mulch, the standard unit of measurement is based on volume rather than weight or area. Understanding the primary volumetric unit used in the industry is the first step in accurately estimating project needs. The industry relies almost exclusively on the cubic yard to quantify these loose materials.
Defining the Cubic Yard
The standard bulk measurement for bark, mulch, and other loose landscaping materials is the cubic yard. A cubic yard is a volumetric unit representing a cube that is three feet long, three feet wide, and three feet high. Mathematically, this volume is equal to 27 cubic feet (3 x 3 x 3). One cubic yard is roughly the size of a large kitchen stove or a standard washing machine, providing the baseline for project coverage calculations.
Calculating Your Project Volume
Determining the exact amount of bark needed requires a straightforward calculation of your project’s total volume. The first step involves measuring the length and width of the area you plan to cover, recording both dimensions in feet. Next, decide on the desired depth of the bark layer, which is typically measured in inches. This depth measurement needs to be converted into feet by dividing the number of inches by 12; for instance, three inches converts to 0.25 feet.
Once all three dimensions—length, width, and depth—are in feet, multiply them together to determine the total volume in cubic feet. Finally, divide the total cubic feet by 27 to arrive at the number of cubic yards to order. For example, a flower bed covering 108 square feet at a depth of three inches (0.25 feet) translates to exactly one cubic yard of material.
Factors Affecting Coverage
While the mathematical calculation provides a precise volume, real-world factors influence the actual coverage achieved by one cubic yard of bark. The most significant variable is the application depth. Most landscape professionals recommend a depth of at least three to four inches to gain maximum benefits, such as effective weed suppression and moisture retention. A two-inch layer is generally considered sufficient only for aesthetic top-dressing.
The type of bark material also plays a role in how the volume spreads. Finer, shredded bark materials tend to compact more tightly, which can slightly reduce their overall spread compared to larger, less dense bark nuggets or chips. Furthermore, a delivered volume may settle over time or compress during the spreading process. Accounting for this natural settling and potential waste by ordering an extra five to ten percent is a practical measure to ensure complete coverage.