Yeah. I make labels quite frequently. You can do 6.5" wide x 4".
That's the quick and easy way. I prefer doing 6.5" wide x 3.875" high, as some bottles have the upper lip by the neck and this sizing won't 'curve' over the lip at all. Homebrew store bought bottles have this upper lip.
Good luck and share some pics!
Edit: 6" wide would suffice too, but I like a wider label going 5/7 the way around
40 Gallons brewed in 2013....and counting
33 Gallons brewed in 2012
159 Gallons brewed in 2011
My Brutus 10