Dumb question??

[kryspykitty.livejournal.com]

Well I am kind of a newbie when it comes to sewing, and even more so when it comes to measurements, etc....so I thought this would be a great place to ask this question!

If I wanted to make a queen size duvet cover how many yards of fabric would I need to get (assuming I am only purchasing fabric for one side, as I plan on using a sheet for the 'back')??

I found some fabric I LOVE at Joanns but am at a total loss as of how much to purchase (and I don't wanna rely on their employees to know as last time I did that I was shorted 2 inches, which was a big deal as I was using the fabric to cover a canvas!!!Doh).:(

Thanks!