Amazon can also process content in EPUB source format. KindleGen compiles the file and runs checks for common errors. Any errors or warnings will prevent the titles from becoming available. These errors must be fixed in the EPUB file before the title is published in the Kindle store.
Marketing Cover Image Is Mandatory
Use the CSS page-break-before and page-break-after attributes.
Anchors tag Must Be Added before Formatting Tags
src tag: (Required) Identifies the embedded audio file, which must be in MP3 format.
The maximum size of an individual image file is 5 MB. The maximum size of an epub is 650 MB.
These fonts can be either Open Type (OTF) or True Type (TTF).
Internal cover image size width minimum 600px.
Body text must not have a forced alignment (such as left aligned or justified).
Body text must use the default font size and line height. Body text should not use the <font size=”…”> tag or the font-size and line-height attributes in CSS.
Body text should not be primarily bold or italicized. Selected parts of the text can be bold or italicized for emphasis.
Body text should not have an imposed font color throughout the book. If you prefer to use imposed font color in some sections of your book, please do not use too light or too dark color. Light colors will not display with enough contrast on devices set to white backgrounds or on e Ink devices. Dark colors will not display well on devices set to black backgrounds. For grays, use colors within the hex value range of #666 to #999.
Body text must not have a white or black font color. Customers report this as a bad user experience because the text can become invisible when the Kindle is set to the same background color as the font.
Body text must not have a black or white background color. Customers report this as a bad user experience because it can create an awkward, boxy reading experience when the device background is set to a different color and because the text can become invisible when a user changes the background color setting on their device and the font color automatically inverts.
Internal Cover Must Not Appear Twice.
Images must be in the JPEG format. Amazon recommends using an image resolution of 300 dpi or 300 ppi.
Amazon does not recommend adding additional guide items to the OPF file, because they will be grayed out in the menu options and may cause customer confusion.
IMPORTANT: Guide items, especially the TOC guide item, do not replace the table of contents.
Kindle does not recommend the use of Type 1 (Postscript) fonts.