To calculate: Measure the length, width, and depth of the area that you plan to cover. Remember to measure the depth in feet (e.g. 4 inches = .333 feet). Multiply the length, width, and depth together. Divide that product by 27 to convert to cubic yards.
Mulch should be applied to a 3 inch depth:
The conversion factor from cubic yards to tons varies depending on the type of material you are using. Materials such as screened topsoil and mulch do not have a good conversion factor, since they retain water weight so well. Here are approximations of weight: topsoil - 1,500 lb, mulch-950 lb, stone products-2,000 lb, sand-2,500 lb