How to Add or Change an EPUB Cover Image (2026)

Every EPUB should have a cover image. It appears in the library grid of every e-reader app, and without one your book displays a generic grey placeholder. This guide shows how to add or replace a cover using Calibre, Sigil, or a manual zip editor — and explains the correct metadata required for the cover to work on all devices.

How EPUB cover images work

An EPUB cover requires two things working together:

1. The image file: a JPEG or PNG inside the EPUB zip (typically images/cover.jpg or cover.jpeg).
2. The metadata declaration: the content.opf manifest must include the image and mark it as the cover.

EPUB 2 and EPUB 3 declare covers differently:

<!-- EPUB 2: meta tag in content.opf -->
<meta name="cover" content="cover-image"/>
<item id="cover-image" href="images/cover.jpg"
      media-type="image/jpeg"/>

<!-- EPUB 3: properties attribute on the manifest item -->
<item id="cover-image" href="images/cover.jpg"
      media-type="image/jpeg" properties="cover-image"/>

Recommended cover image specifications

• Format: JPEG (smaller file size) or PNG (lossless, supports transparency)
• Dimensions: at least 1600 × 2400 px recommended; Kindle requires at least 1000 px on the short side
• Aspect ratio: 2:3 (portrait) — matches most e-reader library grids
• File size: keep under 500 KB; large covers slow loading on older devices
• Color space: sRGB (devices may display CMYK incorrectly)

Add or change cover in Calibre

This is the easiest method for a quick cover change:

1. Add the EPUB to Calibre. Click the book to select it.
2. Click Edit metadata (press E).
3. In the metadata dialog, click the cover image on the right.
4. Click Browse to select a cover image from your file system, or Download cover to fetch one from online sources.
5. Click OK. Calibre writes the image into the EPUB and updates content.opf.

To verify: right-click the book → Open with → EPUB viewer and confirm the cover appears correctly.

Add or change cover in Sigil

Sigil gives you direct control over the EPUB internals:

1. Open the EPUB in Sigil.
2. In the Book Browser panel (left side), right-click Images → Add Existing Files. Select your cover JPEG/PNG.
3. Right-click the newly added image → Add Semantics → Cover Image. Sigil updates the manifest with the cover-image property.
4. For EPUB 2 compatibility: open content.opf in the code editor, find the <metadata> section, and add <meta name="cover" content="YOUR-IMAGE-ID"/>.
5. Save (Ctrl+S). Run Tools → Run All Checks to confirm no errors.

Manual method using a zip editor

An EPUB is a ZIP archive. You can edit it directly without specialized tools:

1. Rename book.epub to book.zip and extract it.
2. Replace images/cover.jpg (or wherever the existing cover is) with your new image — keep the same filename.
3. If adding a new cover (not replacing), also edit content.opf to add the manifest item and cover metadata.
4. Repack: zip -rX book.epub mimetype . --exclude=mimetype (must add mimetype first, uncompressed).
5. Rename book.zip back to book.epub.

The mimetype file must be the first entry in the ZIP and must be uncompressed — this is part of the EPUB spec and some validators check for it.

Why the cover doesn't show up on some devices

• Wrong manifest ID reference: the content attribute of the EPUB 2 meta tag must match the id of the manifest item exactly (case-sensitive).
• Missing cover page: some readers expect a cover XHTML page in addition to the image. Add a simple cover.xhtml that displays the cover image and mark it with epub:type="cover" in the spine.
• Image format issue: convert PNG covers to JPEG for maximum compatibility on older devices.
• Cached metadata: Calibre and some e-readers cache cover thumbnails. If you replaced the cover and still see the old one, right-click → Remove books from library → re-add.