The cover is the one part of an ebook you see every day. A missing or low-quality cover makes an otherwise good book look broken in your library — and if you publish, it is the first thing stores judge. Changing it should take two minutes, not an evening of XML wrangling.
This guide covers the fast way (a dedicated cover changer), the manual way (inside a full editor), and the part most guides skip: the exact dimensions each device actually wants, plus why covers sometimes refuse to update.
How an EPUB Cover Works Under the Hood
An EPUB's cover is two things at once:
- An image file inside the package (usually
cover.jpgin an images folder) - Two declarations in the book's metadata (the OPF file): one marking the image as the cover, one listing it in the manifest
When a cover doesn't show, it is almost always because one of those declarations is missing or points at the wrong file — not because the image itself is gone. This is why "replace the cover" tools are more reliable than manually swapping the image file: they rewrite all the declarations for you.
Method 1: One-Click Cover Changer (Recommended)
The fastest route is a purpose-built tool. The free EPUB cover changer does the whole job in the browser:
- Drop in your
.epubfile. - Upload or pick the new cover image.
- Choose your target device — the tool resizes and embeds the image with the correct declarations for Kindle, Kobo, BOOX and other readers.
- Download the updated book.
Because everything runs locally, the file never leaves your device — worth noting for unpublished manuscripts.
This method is ideal when the book is otherwise fine and you only want a different cover: no chapter editing, no learning curve, done in a minute.
Method 2: Change the Cover Inside a Full Editor
If you are already editing the book — fixing text, updating the metadata — change the cover in the same session with the online EPUB editor:
- Open the book in the editor.
- Open the metadata panel and replace the cover image.
- Make any other edits while you are in there.
- Export. The editor embeds the new cover and keeps the declarations consistent on export.
The editor route is best when the cover is one of several changes, or when the cover reference itself is broken (the "cover missing entirely" case) — an editor shows you the metadata state, not just the image slot.
Cover Size Guide by Device
Covers are judged by aspect ratio more than pixel count. All major readers accept roughly the same tall-book ratio, but each has its sweet spot:
| Device | Recommended size | Aspect ratio | Format |
|---|---|---|---|
| Kindle | 1600 × 2560 px | 1 : 1.6 | JPEG |
| Kobo | 1600 × 2400 px | 1 : 1.5 | JPEG / PNG |
| BOOX | 1600 × 2560 px | 1 : 1.6 | JPEG / PNG |
| PocketBook | 1200 × 1920 px | 1 : 1.6 | JPEG |
| Apple Books | 1600 × 2400 px | 1 : 1.5 | JPEG |
Practical rules that keep you out of trouble:
- 1600 × 2560 JPEG is the safe default — every current reader displays it well
- Keep files under 5 MB; oversized images slow library scrolling on e-ink devices
- Avoid text near the edges — readers crop slightly when displaying thumbnails
- sRGB color profile — covers converted from print profiles can look dull on e-ink screens
For e-ink specifically: high-contrast covers with strong shapes read better than subtle gradients, because 16-level grayscale rendering flattens delicate detail.
Why the New Cover Isn't Showing (and the Fix)
The most common complaint after changing a cover isn't the change — it's the device ignoring it.
The reader cached the old thumbnail. Kindle and Kobo aggressively cache covers. Fix: delete the book from the device completely (not just the library entry — remove the file), re-send the new EPUB, and restart the device if the stale cover persists.
The image isn't declared as the cover. An image file dropped into the package without the <meta name="cover"> declaration is just an illustration, not a cover. The cover changer writes both declarations; manual edits often write only one.
The book has two cover declarations. EPUB 2 and EPUB 3 cover mechanisms can coexist; if they point at different images, readers pick unpredictably. A tool that rewrites both consistently beats hand-editing either.
The image filename has spaces or exotic characters. Some readers fail silently on my cover (final) 2.jpg. Renaming to cover.jpg during the swap avoids the whole class of problem.
Send-to-Kindle shows the old cover. Kindle's conversion caches by title. Change nothing except re-sending, and you may get the old art; re-send after fixing the metadata (title + author) and the fresh cover follows. Check the whole file with the EPUB checker if the behavior is odd.
Where to Get a Good Cover Image
- Your own design: any image editor works; keep the ratio, keep it simple
- Public-domain art: Project Gutenberg and museum archives (Rijksmuseum, Met) offer high-resolution files free to use
- Stock photos: ensure the license covers ebook distribution if you publish
- Recovering the original: if you only want to extract a cover from another book, the cover extractor pulls the embedded image out in one step
Frequently Asked Questions
Can I change the cover of a book I bought? If the file is DRM-free, yes — open it with any of the methods above. DRM-protected purchases cannot be modified.
What format should an EPUB cover be? JPEG is the most compatible choice. PNG works everywhere that matters but produces larger files for photographic covers. Stick to JPEG unless the cover is flat graphic art.
Does a bigger cover image mean better quality on screen? Only up to the screen's capability. A 1600 × 2560 image already exceeds every e-reader display; doubling the size just bloats the file and slows the library.
Will changing the cover change how the book opens? No — the reading content is untouched. The only visible difference is the thumbnail in your library and any cover page inside the book you chose to replace.
Change It Now
The one-minute version: open the EPUB cover changer, drop in your book, pick a 1600 × 2560 JPEG, download. If you're editing the book anyway, the EPUB editor handles the cover alongside everything else.