What Files Do Retailers Accept?

We understand that knowing which files each retailer accepts is difficult to keep track of, so we created this Retailer Quick Guide for easy reference. If you are unsure whether your converted eBook file will be allowed at a retailer, please download the full guide attached.

File Type Restrictions

Special restrictions that require more explanation are noted below. For the full extent of which files are accepted at the retailers, download the attached guidelines. Validations are based on retailer requirements and processed on a per file-type basis, see: File and Cover Image Validations.

Custom Samples


Custom samples files are required for the following types of eBooks: iBooks Author (See instructions), Read Along (EPUB 2.0 or EPUB 3.0), and Interactive (EPUB 2.0 or EPUB 3.0). 


Custom sample files are required for files with audio or video. See See Section 6.17



Screenshots are only required for .ibooks files but any book has the option to display screenshots of the book on an Apple device (on how to take a screen shot, consult the appropriate device manual: http://support.apple.com/manuals/#ipad). 

You must follow these guidelines:

  • Screenshots must be 1024 x 768, 768 x 1024, 2048 x 1536, or 1536 x 2048 pixels, in the RGB color space, and in the JPG or PNG file format.
  • Status bars can be removed from screenshots, in which case the resolution requirements are 1024 x 748, 768 x 1004, 2048 x 1496, or 1536 x 2008 pixels.
  • Screenshots in other formats and sizes will be rejected. 
  • Cover Art as Screenshot. Do not use the book’s cover as a screenshot.
  • Accuracy. Screenshots must accurately represent the book.

Amazon MOBI Files

These files are automatically generated for Amazon upon ingestion using KindleGen (unless a custom MOBI file has also been sent). EPUB files must be properly formatted for this conversion, see Amazon Kindle Publishing Guidelines. INscribe recommends that all EPUB files be optimized for KindleGen conversion. NOTE: Fixed Layout files require a custom unique fixed layout MOBI file. Region Magnification in MOBI files require the following OPF tags: <meta name="RegionMagnification" content="true"/> <meta name="book-type" content="children"/> (or: <meta name="book-type" content="comic"/>)

EPUB 3.0

Not all retailers are ready to launch EPUB 3.0 files. Please consult the guide for an updated list of file acceptability.

We offer EPUB 3.0 to EPUB 2.0 file downgrading at just $20 per file. Please place a Conversion Quote request if interested in this service.


Retailers that do accept EPUB 3.0 don't support the standard across all of their older devices or available platforms, so be sure to create files that are backwards compatible to EPUB 2.0, especially:

  • Still include the <meta> tag for the cover image
  • Include the .ncx TOC for EPUB 2.0 readers

  • Include the <guide> section for EPUB 2.0 readers
  • Use CSS3 that degrades gracefully: CSS3 wasn't used in EPUB 2.0 (CSS 3)
  • Use fallbacks for Core Media Types
  • When embedding video or audio use fallbacks to describe the content or link to online copies, see Fallbacks in: Multimedia support in EPUB 3.0

EPUB 3.0 Versioning

Version information can be declared in the OPF file of your EPUB 3.0 file. Retailers use this information on their storefronts to let customers know when updates have been made to an eBook they have purchased. 

Book versioning is optional, but if you use it once, you must continue to use it in every iteration after. This means that you will need to update the version number whenever a new file is sent. Start with 1.0 and then go up using dot-separated integers. We recommend 1.1, 1.2, etc. for minor changes and 2.0, 3.0 for major changes. There is a maximum of two dots, three components, and four integers per component (for example: 1111.1111.1111). 

Due to the complexity, INscribe recommends that you do not use iBooks version numbers unless you have a way to ensure that you can track it and manage it correctly.

Additionally, you MUST notify us through a help desk ticket when you want to replace the file with a new version and you need to also submit a "What's new in this version?" description. iBooks will not process your new file until they have received the "What's new in this version?" description. Even if reverting to a prior revision due to editor suggestions, still go up in the version number and note in the description that it is a reversion to a prior version.

For iBooks: To use book versioning in iBooks for EPUB 3, you must include the following prefix attribute in the <package> element in the OPF file:

<package xmlns="http://www.idpf.org/2007/opf" unique-identifier="bookid" version="3.0" prefix="ibooks: http://vocabulary.itunes.apple.com/rdf/ibooks/vocabulary-extensions-1.0/">

Note: In the prefix example above, the space between ibooks: and http:// is important; it needs to be a single, regular space character and not a return, non-breaking space, or any other kind of whitespace.

Note: The version of your book is specified within a meta element in the Package Document. The meta element has a property value of "ibooks:version": <meta property="ibooks:version">1.1.2</meta>

Rolling Back to EPUB 2.0

Reverting back to a EPUB 2.0 file: If the current file is EPUB 3.0 and you would like to revert back to a file that is EPUB 2.0, you must submit the title under a new ISBN and then take down the title with the ISBN that is associated to the EPUB 3.0 file. (iBooks store: If you submit an EPUB 2.0 file to replace an EPUB 3.0 file, you will see in the error report: ERROR ITMS “Provided asset version is not greater than the existing live asset version.  Provided = 2.0   Live = 3.0" at Book (MZItmspBookPackage):”

PDF Files

PDF files must be eBook ready, optimized for size, fully OCR’d, with embedded fonts. Bookmarks should also be set at Table of Content starting points. PDF files may be previewed in Adobe Digital Editions to confirm styling and page dimensions.  Adobe Digital Editions (free download):  http://www.adobe.com/products/digitaleditions/  


All fonts must be Open Type or True Type.

Pricing Restrictions

Some retailers limit the pricing structures allowed on their store fronts. Many library outlets do not support free or even prices up to $2.99 USD. Please review the attached guide for more details.