How to Change an EPUB Book Cover

Why changing a cover is more than swapping a file

In an EPUB the cover is referenced in more than one place. The manifest lists the image file. A marker says which manifest item is the cover: a cover-image property in EPUB 3, a cover metadata entry in EPUB 2. Often a small XHTML page in the reading order shows the same image as the first page. Replacing the file without keeping those pieces consistent is the usual reason a cover goes blank, shows twice, or stays old.

Steps

1. Open the EPUB Cover Editor and choose the book. The current cover, if the book has one, is shown.
2. Choose the new image on the right. A preview appears.
3. Press Save EPUB with new cover.
4. Download the new file and import it into your reading app.

Everything happens in the browser; neither the book nor the image is sent to a server.

What the tool does behind the scenes

• Same format, new image: the cover file is replaced in place; references stay as they are.
• Different format: a JPEG replaced by a PNG gets a .png name; the manifest’s file name and media type are updated; every reference to the old path in XHTML, CSS, SVG and navigation files is rewritten.
• No cover yet: a cover item is added to the manifest, flagged as the cover image, with the EPUB 2 style metadata entry alongside.
• Afterwards: the output is re-opened and validated so you see errors immediately.

Choosing the image

The tool does not resize or recompress your image. If it is too large, shrink it in an image editor first.

The new cover does not appear in my app

1. Remove the book from the app and import the edited file. Apps copy the cover when a book is first added and often do not refresh it.
2. If the app uses a cloud library, delete the cloud copy as well.
3. Check the book with the validator. Errors about the manifest or missing files can prevent a cover from being identified.
4. Try another reading app to see whether the problem is in the file or in the first app’s cache.

A cover changes only the image. To correct the title or author at the same time, use the metadata editor; the cover editor does not alter those fields.

Fixing a cover that is the wrong shape

Reading apps display covers in a portrait frame. A landscape image or a square one is letterboxed or cropped, which can cut off a title. Before adding an image, prepare it in any image editor: crop or extend the canvas to a portrait ratio around 2:3, keep the title well inside the edges, and export as JPEG at moderate quality. The cover editor embeds exactly what you give it and never crops.

Cover image versus title page

Some books also contain a first page in the reading order that shows the cover image, so the book opens with a picture. That page and the cover image used for the library thumbnail are separate in the package. The editor keeps both consistent when the image type is unchanged, and rewrites page references when the file name changes. If a book has a decorative first page that uses a different image, that page is left alone.

Accessibility

A cover is an image, so it should have a text alternative. The editor does not add one, because the right text depends on the book. If you are producing books for others, add alt text to the cover page’s image tag in your authoring tool.

Troubleshooting by symptom