Mulch Calculator How much mulch do you need? Use our Mulch Calculator and find out. Enter the dimensions of the area you want to cover as well as the desired depth, click Calculate and the results will appear below. Length: (feet) Width: (feet) Depth: Please Select One 2 inches 3 inches 4 inches Calculate You will need approximately:* cubic yards of mulch. or* (3 cubic foot) bags. *Please round all values up to ensure proper coverage. Reset