Hello,

1 foot deep of topsoil is very deep and may mat down unless amended with some compost. If you would like to consult about your project, please give MSU Extension Garden Hotline a call<personal data hidden>), or write back to us with some details on where this will be applied, and what will be grown.

In answer to your question:

I used the "Method 1" formula in the calculator link, below:

830sq feet X 1 ft deep = 830 cubic feet.

830 sq ft X 12 inches deep X .0031= 30.88 cubic yards

Here is Darren Bagley's calculation, who also consulted on your question, for topsoil in 40lb bags---

"You may also wish to get a topsoil/compost mix, depending on what you are growing. You may wish to purchase topsoil/compost in bulk from a landscaping company, rather than in bags. When you acquire topsoil/compost, you might wish to ask for references, just like you do for any other professional service.

A 40-lb bag of topsoil is about .75 cubic feet (or ft3). 

830 ft2 X 1 foot deep = 830 ft3 

830 ft3/.75 ft3 = 1106.66 bags of topsoil."

Note that the 40 lb bag volume varies somewhat depending on moisture content. 

Calculator: link:

http://aggie-horticulture.tamu.edu/travis/wp-content/uploads/2013/06/HowMuchDoINeed2010.pdf

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