This question seems to be a popular one in this forum. A lot of people want to know how to figure out the correct amount of mulch for their landscaping project. So D Felix came up with a good idea to have the formula stuck to the top of this forum. Here it is: To determine how much mulch is needed, you take: Total square feet x depth desired (in feet) / 27 = cubic yards needed Figure out your square footage. Take square footage time depth desired (in feet, i.e. 3" = .25 feet). That gives volume in cubic feet. Divide that number by 27 to get cubic yards. There's 27 cubic feet per yard (3'x3'x3'=27 cubic feet).