Once I finished my first pouch, I decided to make one a little larger just to be sure. The first pouch used a 6-inch zipper and the finished size is 5 inches x 6 1/2 inches. My modified one used a 7-inch zipper and measures 6 1/2 inches x 8 inches.
I do like the smaller original pouch better for this project so I'm going to start making many more. The link to the tutorial can be found here. As for the larger one, I think because there is no interfacing in them, they seem too weak to hold stuff. Maybe I will try a quilted version of this one sometime to give it more heft.