How much topsoil will i need to cover 880 square feet?

That depends on the depth of the topsoil you will put down. Multiply the number of square feet by the depth of topsoil--that will give you the number of cubic feet. To convert to cubic yards, divide the number by 27.

So, for example, if you are using 3" of topsoil over 880 square feet then your calculation would be:

880 times .25 (3" = .25 feet) = 220 cubic feet (divided by 27--there are 27 cubic feet in a yard) equals 8.15 cubic yards.