Bark dust is an organic mulch composed of shredded tree bark, typically from Douglas fir or hemlock trees. It is widely used in landscaping to cover the soil surface, providing a clean and uniform aesthetic to garden beds and pathways. Beyond visual appeal, this material serves important functional roles, including moderating soil temperature and significantly reducing water loss from evaporation. Determining the exact volume required prevents the inconvenience and expense of over- or under-ordering. This reliable, step-by-step guide walks you through the precise measurements and calculations needed for your project.
Measuring the Area for Coverage
The first step in calculating your material needs is accurately determining the square footage of the area you intend to cover. For standard, uniformly shaped planting beds, measure the length and width of the space in feet using a tape measure. You will multiply these two dimensions together to find the total square footage of the area.
Handling irregularly shaped areas requires a different approach. Divide the complex area into a series of smaller, manageable geometric shapes, such as squares, rectangles, or triangles. Calculate the square footage of each smaller section individually, and then add those figures together for the total area. It is recommended to round measurements up to the nearest half or whole foot to provide an allowance for material loss or uneven edges.
Selecting the Optimal Depth
Choosing the appropriate depth for your bark dust application directly impacts its effectiveness and the total volume you will need to purchase. For purely aesthetic top-dressing or refreshing an area that already has a base layer, an application depth of one to two inches is typically sufficient. This thinner layer provides a finished look and helps conserve some soil moisture.
However, if your primary goal is effective weed suppression over bare ground or maximizing moisture retention, a deeper layer is necessary. A depth of three to four inches creates a physical barrier that blocks sunlight, preventing weed seeds from germinating and sprouting. Maintaining this consistent depth, measured in inches, is necessary before proceeding to the volume calculation.
Calculating the Volume Needed
The mathematical process for determining the volume of bark dust required involves multiplying the three physical dimensions of your area: length, width, and depth. To perform this calculation accurately, all measurements must be in the same unit, which will be feet. Since you have already measured the length and width in feet, the depth measurement in inches must be converted to a fraction of a foot by dividing it by twelve.
For example, a three-inch depth converts to 0.25 feet (3 inches divided by 12 inches per foot). Once all dimensions are in feet, multiply them together to find the volume in cubic feet (Length x Width x Depth).
Because bark dust is sold in bulk by the cubic yard, you must convert the cubic footage total into cubic yards. Divide the number by 27, as there are 27 cubic feet in one cubic yard. If you have an area of 500 square feet and plan to apply a three-inch depth (0.25 feet), the calculation is 500 x 0.25 = 125 cubic feet, which then converts to 125 divided by 27 = 4.63 cubic yards.
Practical Ordering and Delivery Logistics
Once you have calculated the necessary volume in cubic yards, you can move on to the purchasing phase. You will generally choose between buying in bulk by the cubic yard or purchasing bagged material, which is typically sold by the cubic foot or quart. Buying in bulk is usually the more cost-effective choice for large projects, while bagged material is often more convenient for smaller jobs or areas with limited access.
It is advised to round your final calculation up to the nearest whole or half cubic yard when placing your order. This slight overage accounts for factors like material settling over time, minor inconsistencies in application depth, and some inevitable loss during spreading. When arranging delivery, confirm that the designated dump location is easily accessible for the delivery truck and is clear of obstructions.