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How to Add a Cover Image to an EPUB
EPUB supports embedded covers, but readers can be picky. Learn best sizes, common failures, and a fix checklist.
TL;DR
- Embed the cover image inside the EPUB.
- Include a cover image and a cover page.
- Keep file size reasonable (avoid huge PNGs).
- Some readers require correct metadata and cover XHTML.
- For reliable display, configure both cover metadata and an explicit cover page in the spine.
Why covers don’t show
Missing metadata, missing cover page, oversized images, or reader cache issues are the usual causes.
Some readers only display covers after re‑importing the book; they cache old cover data aggressively.
Cover troubleshooting checklist
Confirm the image is embedded, use JPG/PNG, include a cover page, re‑import the book, and test another reader.
If a cover still doesn’t display, validate the EPUB structure and confirm the manifest entry uses the correct MIME type.
How to add a cover in a converter
Most converters can embed a cover in a few steps.
Cover Specification Checklist
Use a single JPG or PNG cover with clean contrast and predictable aspect ratio. Extremely large covers inflate file size and slow first-open performance on lower-end devices.
Always verify that the cover appears in two places: as library thumbnail and as first reading page. Some readers rely on metadata image flags, while others rely on the first spine item.
If your source PDF has a full-page first image, use it only when no additional text or layout elements exist outside the image object. Otherwise upload a dedicated cover asset.
Recommended cover specs
| Item | Recommendation |
|---|---|
| Ratio | ~1:1.6 |
| Size | 1600×2560 px (approx.) |
| Format | JPG for photos, PNG for sharp text |
| File size | Aim < 1–2 MB |
How to add a cover in a converter
- Choose your cover image.
- Enter title/author metadata.
- Export as EPUB3.
- Test in two readers.
Common mistakes
- Shipping a huge PNG “for quality.”
- Setting cover metadata but missing a cover page.
- Updating cover without re‑importing the book in a reader.
- Using unusual file types or missing MIME types.
- Relying on image metadata only without adding a cover page to reading order.
FAQ
Can EPUB include a cover inside the file?
Yes. It’s typically embedded as an image within the EPUB container.
What’s the best cover size?
Around 1600×2560 px is a solid default; keep file size reasonable.
Why does my cover show on one app but not another?
Readers interpret cover metadata differently; include metadata + cover page.
Does the cover affect SEO?
Not inside the EPUB, but covers help perception and sharing.
Why does a cover appear in one reader but not another?
Readers prioritize different cover signals (metadata, manifest properties, spine order). Include all required cover references for maximum compatibility.
Sources and references
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