Size: 100MB or less. Please note, while IngramSpark and retail sites can accept 100MB files, the IDPF Validator cannot check files over 10MB due to the amount of time it would take.
Format: Must be EPUB Check 3.0.0 compliant. We cannot accept enhanced EPUB 3 files at this time. No single image inside an ePub can be greater than 3.2 million pixels. (Total pixels = length in pixels X width in pixels).
Include an internal cover image. This should be formatted the same size of, and as part of your interior. (For use within the book content.)
Be sure the metadata entered in IngramSpark matches the information on your cover. For example, if the cover art and the book asset are for a book titled Paradiso, but the metadata is for Purgatorio, then the items do not match.
There should not be any reference to page numbers in the book. This includes the Table of Contents. Your e-book will never look just like your print book. E-readers are limited in the way they display content and your book will appear different from device to device.