The best size for an eReader is a 6-inch screen. That has become the industry standard for Kindles, Kobos, and more. It’s roughly the size of a typical mass-market paperback book. You can always adjust the text size if needed. For storage sizes, anything bigger than 2 GB will house at least a thousand books or more, enough for the typical reader. Currently, 8 GB seems to be the norm for all popular eReaders, and most offer a 32 GB model at a higher price point.