Originally Posted by AnemicOak
It's possible you'd have to buy more space it depends on your library size and how much free space you have. Through referrals and things you can do to get more space I have a total 18.2GB (IIRC you start out with 2GB free) and IIRC some other services give you more free space to start out. My Calibre library is about 2,800 books with almost all of them in both ePub and Mobi format and takes up about 3GB.
Thank you for this information. I'm been considering several options to get the books to my iPad. It's good to know all my options.