Topsoil is typically sold by the bag at home improvement or gardening supply stores. A 40-pound bag of topsoil covers approximately one cubic foot, and ranges from $2 to $5 per bag. The cost variations usually come from the quality of topsoil and whether it includes composted material or was mixed with fertilizers and other growth-stimulating products. When estimating materials and cost for a gardening project, calculate the total cubic feet before running off to the store to buy topsoil.
To calculate total cubic feet, multiply the length, width and depth of the area requiring the soil. For example, if you want to level a flower bed that is 12 feet wide by 3 feet long and 1 foot deep, the calculation is: 12 x 3 x 1 = 36 cubic feet. At a cost of $2 to $5 per bag, the total would be between $72 and $180.
Topsoil sold by the bag is not always the best value. Nurseries are well stocked with dirt and gravel and capable of providing large amounts of topsoil for much less than the cost of bagged bargain-store brands, in most cases. Nurseries will also deliver the topsoil, meaning all you have to do is spread it over the area after it is dropped off.
Topsoil does not last forever. It is usually necessary to spread topsoil over flowerbeds and lawns at least once a year. This is a prime consideration when calculating landscaping costs year over year.